2.2 Maturity Levels in the People CMM
A capability maturity model (CMM) is constructed from the essential practices of one or more domains of organizational process. The People CMM concerns the domain of workforce management and development. A CMM describes an evolutionary improvement path from an ad hoc, immature process to a disciplined, mature process with improved quality and effectiveness.
All CMMs are constructed with five levels of maturity. A maturity level is an evolutionary plateau at which one or more domains of the organization's processes have been transformed to achieve a new level of organizational capability. Thus, an organization achieves a new level of maturity when a system of practices has been established or transformed to provide capabilities and results the organization did not have at the previous level. The method of transformation is different at each level, and requires capabilities established at earlier levels. Consequently, each maturity level provides a foundation of practices on which practices at subsequent maturity levels can be built. In order to be a true CMM, the maturity framework underlying a model must use the principles established in Humphrey's maturity framework for transforming the organization at each level.
The People CMM applies the principles of Humphrey's maturity framework to the domain of workforce practices. Each of the People CMM's five maturity levels represents
a different level of organizational capability for managing and developing the workforce. Each maturity level provides a layer in the foundation for continuous improvement and equips the organization with increasingly powerful tools for developing the capability of its workforce. The nature of the transformation imposed on the organization's workforce practices to achieve each level of maturity is depicted in Figure 2.1.
FIGURE 2.1 The five maturity levels of the People CMM
Source: Adapted from Humphrey  and Carnegie Mellon University  with permisson.