Home > Articles > Programming

Preface to The Incremental Commitment Spiral Model: Principles and Practices for Successful Systems and Software

  • Print
  • + Share This
Do your projects overrun their budgets and schedule or have a lot of late rework or technical debt? Are your delivered systems hard to maintain? Do your systems need to succeed in situations involving rapid change, emergent requirements, high levels of assurance, or some combination of those? If so, then this might be the right book for you.
From the book

Who Can Benefit from Reading This Book?

The book’s contents can help you if you face one or more of the following situations:

  • Your projects frequently overrun their budgets and schedule.
  • Your projects have a lot of late rework or technical debt.
  • Your delivered systems are hard to maintain.
  • Your organization uses a one-size-fits all process for a variety of systems.
  • Your systems need to succeed in situations involving rapid change, emergent requirements, high levels of assurance, or some combination of those.
  • Your systems must operate with other complex, networked systems.

Managers and executives stuck in one-size-fits-all decision sequences will find new possibilities and begin to understand their new roles in successful 21st-century development. Practitioners of all development-related disciplines will find a unified way to approach a broad variety of projects, improve their collaboration, respond more agilely to the changing needs of stakeholders, and better quantify and demonstrate progress to managers and executives. Academics will gain a source of information to replace or enhance the way they educate developers and managers, as well as fertile areas for research and study.

As one-step, total-makeover corporate process changes can be risky, this book provides a way for organizations or projects to incrementally experiment with the ICSM’s key practices and to evolve toward process models better suited to their needs and competitive environment.

An Electronic Process Guide (EPG), available on the book’s companion website (http://csse.usc.edu/ICSM), contains guidelines, subprocesses, and templates that facilitate ICSM adoption. The EPG also supports this volume’s use as a textbook for a capstone project course in systems or software engineering. USC has offered such a course since 1995, spanning and evolving across more than 200 real-client projects and 2000 students.

How Is the Book Organized?

The book generally flows from why, moves to what, and then on to how, with a bit of how much in between. It begins with a Prologue—a cautionary tale drawn from ancient mythology, but highly relevant to 21st-century system developers.

Once suitably enlightened, the reader will find a one-chapter Introduction describing our rationale for constructing the ICSM and a high-level, self-contained overview of ICSM fundamentals and use. System development stakeholders (e.g., users, developers, acquirers), executives, and managers may obtain a big-picture understanding of the ICSM, and find the summary to be food for thought and action in managing the uncertainties of modern complex product or system development. Readers who would prefer to start by exploring a particular aspect of the ICSM can generally use the Contents list or Index to find and address it in detail, but will often find it useful to refer back to the Introduction for overall context.

Part I provides detailed discussions of the four key ICSM principles and explains why they are critical. Each chapter in Part I begins with a failure story and a success story, illustrating the need for and application of the principle, followed by its key underlying practices. Part I completes the why part of the book begun in the Prologue and continued in the early part of the Introduction.

Parts II and III explain the phases and stages that provide the framework for ICSM’s process generation. They introduce the case study that we use to illustrate how the stages and phases of the ICSM support success. This case study uses a next-generation medical device—an example of an advanced cyber–physical–human system with the inherent challenges of assuring safety, usability, and interoperability with other devices and systems—to lead the reader (and the medical device team) through the individual stages and phases of the ICSM. Parts II and III contain the majority of the what information, and a bit of the how.

Part IV completes the how and how much information. It supports implementation of the ICSM through phase-combining patterns and a set of common cases encountered in applying the risk-based phase decisions. There is information on adapting the ICSM to a specific project or environment, and an exploration of how its risk-driven, adaptive framework acts as a unifying element to support the effective application of existing practices. Part IV also provides guidance on applying some key practices that must be adapted somewhat for ICSM, and ends with an afterword that describes how we intend to evolve the ICSM with help from you, the reader.

The Appendices provide additional information on the tools developed specifically for ICSM activities, mappings of the ICSM to widely used process model and standards, and a comprehensive bibliography.

As stated earlier, the Companion Website to the book (http://csse.usc.edu/ICSM) provides the EPG and other automated tools, along with updates, examples, discussions, and useful classroom materials. The website is the primary place to find up-to-date information concerning the ICSM and its use, including white papers and guides for ICSM application in particular domains. While most of the material on the site is free, on occasion there may be material for sale. For those cases, the site is linked to and supported by Addison-Wesley and InformIT to provide an easy means to purchase those materials as well as other books of interest to the readers.

Who Helped Us Write the Book?

The organization and content of the ICSM have benefited significantly from our participation in three major efforts to provide improved guidelines for systems and software practice and education:

  • The U.S. National Research Council’s Human–System Integration in the System Development Process study
  • The international efforts to define educational and practice guidelines that better integrate software, hardware, and human systems engineering—the Graduate Software Engineering Reference Curriculum
  • The Systems Engineering Body of Knowledge and Graduate Reference Curriculum for Systems Engineering

These not only helped improve the ICSM, but also established its compatibility with these reference guidelines, along with co-evolving guidelines such as the IEEE-CS and ISO/IEC’s Software Engineering Body of Knowledge and INCOSE Systems Engineering Handbook.

Funding for much of the initial work on the ICSM was provided through the Systems Engineering Research Center—a U.S. Department of Defense university-affiliated research center. In particular, Kristen Baldwin, Principal Deputy in the Office of the Deputy Assistant Secretary of Defense for Systems Engineering, provided early vision, guidance, and resources to the authors.

The following reviewers provided excellent advice and feedback on early versions of the book: Ove Armbrust, Tom DeMarco, Donald Firesmith, Tom Gilb, Paul Grünbacher, Liguo Huang, DeWitt Latimer IV, Bud Lawson, Jürgen Münch, George Rebovich, Jr., Neil Siegel, Hillary Sillitto, Qing Wang, Da Yang, and Wen Zhang.

The authors have gained numerous insights from collaborations and workshops with our Industrial Affiliate members, including:

Aerospace Corporation: Wanda Austin, Kirstie Bellman, Myron Hecht, Judy Kerner, Eberhardt Rechtin Marilee Wheaton

Agile Alliance: Kent Beck, Alistair Cockburn, Jim Highsmith, Ken Schwaber

AgileTek: John Manzo

AT&T: Larry Bernstein

BAE Systems: Jim Cain, Gan Wang

Bellcore: Stuart Glickman

Boeing: Ray Carnes, Marilynn Goo, Tim Peters, Shawn Rahmani, Bill Schoening, David Sharp

C-Bridge: Charles Leinbach

Cisco: Sunita Chulani, Steve Fraser

CMU-SEI: Roger Bate, Paul Clements, Steve Cross, Bill Curtis, Larry Druffel, John Goodenough, Watts Humphrey, Paul Nielsen

Construx, Inc.: Steve McConnell

Cubic Corporation: Mike Elcan

EDS: Mike Sweeney

Fraunhofer-IESE: Dieter Rombach

Fraunhofer-Maryland: Vic Basili, Forrest Shull, Marvin Zelkowitz

Galorath: Dan Galorath, Denton Tarbet

GE Systems: Paul Rook

General Dynamics: Michael Diaz

Group Systems: Bob Briggs

Hughes: Elliot Axelband

IBM/Rational: Tim Bohn, Grady Booch, Peter Haumer, Ivar Jacobson, Per Kroll, Bruce McIsaac, Philippe Kruchten, Walker Royce

Intelligent Systems: Azad Madni

ISCAS: Mingshu Li, Qing Wang, Ye Yang

ITT/Quanterion: Tom McGibbon

JPL: Jairus Hihn, Kenneth Meyer, Robert Tausworthe

Lockheed Martin: Sandy Friedenthal, John Gaffney, Gary Hafen, Garry Roedler

Master Systems: Stan Rifkin

Microsoft: Apurva Jain

MITRE: Judith Dahmann, George Rebovich

Motorola: Dave Dorenbos, Nancy Eickelmann, Arnold Pittler, Allan Willey

Naval Postgraduate School: Ray Madachy

NICTA: Ross Jeffery

Northrop Grumman/TRW: Frank Belz, George Friedman, Rick Hefner, Steve Jacobs, Alan Levin, Fred Manthey, Maria Penedo, Winston Royce, Rick Selby, Neil Siegel

OGR Systems: Kevin Forsberg

Price Systems: Arlene Minkiewicz, David Seaver

Raytheon: Anthony Peterson, Quentin Redman, John Rieff, Gary Thomas

RCI: Don Reifer

SAIC: Dick Fitzer, Tony Jordano, Beverly Kitaoka, Gabriel Lengua, Dick Stutzke

San Diego State University: Teresa Larsen

Softstar Systems: Dan Ligett

Software Metrics: Betsy Clark, Brad Clark

Stevens Institute: Art Pyster

Teledyne Brown Engineering: Douglas Smith

University of Massachusetts: Lori Clarke, Lee Osterweil

University of Texas: Dewayne Perry

University of Virginia: Kevin Sullivan

Wellpoint: Adam Kohl

Xerox: Peter Hantos, Jason Ho

Finally, the authors are grateful for the support of their partners in life, who put up with working weekends, late nights, unexpected travel, and all of the household inconveniences that writing books entail. To Sharla, Mike, Sohrab, and Jo—our best friends, greatest inspirations, sharpest critics, and truest loves—our heartfelt thanks. We love you.

Praise for The Incremental Commitment Spiral Model

The Incremental Commitment Spiral Model is an extraordinary work. Boehm and his colleagues have succeeded in creating a readable, practical, and eminently usable resource for the practicing systems engineer. . . . ICSM embodies systems thinking and engineering principles and best practices using real-life examples from many different application domains. This is exactly the kind of treatment that an engineer needs to translate the book’s considerable wisdom into practical on-the-job solutions.”

—George Rebovich, Jr., Director, Systems Engineering Practice Office, The MITRE Corporation

“One might think of this new book as an update of the old (1988) Spiral Model, but it is actually much more than that. It is a ground-breaking treatment that expertly blends together four specific and key principles, risk–opportunity management, the use of existing assets and processes, and lessons learned from both success and failure examples and case studies. This extraordinary treatise will very likely lead to improvements in many of the current software development approaches and achieve the authors’ intent ‘to better integrate the hardware, software, and human factors aspects of such systems, to provide value to the users as quickly as possible, and to handle the increasingly rapid pace of change.’ If one is looking for specific ways to move ahead, use this book and its well-articulated advancements in the state-of-the-art.”

—Dr. Howard Eisner, Professor Emeritus and Distinguished Research Professor, George Washington University

“Dr. Boehm and his coauthors have integrated a wealth of field experience in many domains and created a new kind of life cycle, one that you have to construct based on the constraints and objectives of the project. It is based on actively trading off risks and demonstrating progress by showing actual products, not paper substitutes. And the model applies to everything we build, not just software and conceptual systems, but also to hardware, buildings, and garden plots. We have long needed this experience-based critical thinking, this summative and original work, that will help us avoid chronic systems development problems (late, over-budget, doesn’t work) and instead build new life cycles matched to the circumstances of the real world.”

—Stan Rifkin, Principal, Master Systems

“Barry Boehm and his colleagues have created a practical methodology built upon the one fundamental truth that runs through all competitive strategies: The organization with the clearest view of cold, brutal reality wins. Uniquely, their methodology at every stage incorporates the coldest reality of them all—the customer’s willingness to continue paying, given where the project is today and where it is likely ever to be.”

—Chet Richards, author of Certain to Win: The Strategy of John Boyd Applied to Business

“I really like the concept of the ICSM and have been using some of the principles in my work over the past few years. This book has the potential to be a winner!”

—Hillary Sillito, INCOSE Fellow, Visiting Professor University of Bristol, formerly Thales UK Director of Systems Engineering

The Incremental Commitment Spiral Model deftly combines aspects of the formerly isolated major systems approaches of systems engineering, lean, and agile. It also addresses perhaps the widest span of system sizes and time scales yet. Two kinds of systems enterprises especially need this capability: those at the ‘heavy’ end where lean and agile have had little impact to date, and those that deal with a wide span of system scales. Both will find in the ICSM’s combination of systems approaches a productive and quality advantage that using any one approach in isolation cannot touch.”

—James Maxwell Sutton, President, Lean Systems Society and Shingo Prize winner

“The potential impact of this book cannot be overstressed. Software-intensive systems that are not adequately engineered and managed do not adequately evolve over the systems life cycle. The beauty of this book is that it describes an incremental capability decision path for being successful in developing and acquiring complex systems that are effective, resilient, and affordable with respect to meeting stakeholders’ needs. I highly recommend this book as a ‘must read’ for people directly involved in the development, acquisition, and management of software-intensive systems.”

—Dr. Kenneth E. Nidiffer, Director of Strategic Plans for Government Programs, Software Engineering Institute, Carnegie Mellon University

“This text provides a significant advance in the continuing work of the authors to evolve the spiral model by integrating it with the incremental definition and the incremental development and evolution life-cycle stages. Case studies illustrate how application of the four principles and the Fundamental Systems Success Theorem provides a framework that advances previous work. Emphasis is placed throughout on risk-based analysis and decision making. The text concludes with guidance for applying ICSM in your organization plus some helpful appendices. We concur with the authors’ statement: ‘we are confident that this incarnation of the spiral model will be useful for a long time to come.’”

—Dick Fairley, PhD, Software and Systems Engineering Associates (S2EA)

“This book nicely integrates the different refinements of the spiral model and the various additions made over the years. . . . the book contains great material for classes on software engineering in general and software processes in particular. I have been teaching the spiral model and its invariants for more than 10 years now, and I will use material from this book in the years to come.”

—Paul Grünbacher, Associate Professor, Johannes Kepler University Linz, Head of the Christian Doppler Lab for Monitoring and Evolution of Very-Large-Scale Software Systems

“What I found most useful in The Incremental Commitment Spiral Model were the stories of where we have gone wrong in the past, and how using the four key ICSM principles articulated by Barry and his co-authors could have helped these failed efforts maintain a course to success. ICSM is not a new method. It does not ask you to discard what has proved useful in the past and start over. Rather, it provides a set of guideposts that can help any organization facing increasingly challenging endeavors make more timely evidence-based decisions. We have been hearing about the ‘what’ for many years, this book gives you the needed ‘how’ and, more importantly, the needed ‘how much’ guidance that has been sorely missing.”

—Paul E. McMahon, author of Integrating CMMI and Agile Development

“The authors are uniquely qualified to bring together a historical context and a modern problem: successful development of engineered systems with ever greater complexity and richer than ever functionality, enabled by software. They do not disappoint!”

—Dinesh Verma, PhD, Professor and Dean, School of Systems and Enterprises, Stevens Institute of Technology


  • + Share This
  • 🔖 Save To Your Account

InformIT Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from InformIT and its family of brands. I can unsubscribe at any time.


Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information

To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.


Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites, develop new products and services, conduct educational research and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.


If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@informit.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information

Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.


Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.


This site is not directed to children under the age of 13.


Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information

If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.


Users can always make an informed choice as to whether they should proceed with certain services offered by InformIT. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.informit.com/u.aspx.

Sale of Personal Information

Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents

California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure

Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.


This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact

Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice

We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020