A Capability Maturity Model® (CMM®) contains the essential elements of effective processes for one or more bodies of knowledge. Like other CMMs, Capability Maturity Model Integration® (CMMI) provides guidance to use when developing processes. Maturity models are not processes or process descriptions. The actual processes used in an organization depend on many factors, including application domain(s), organization structure, and project size.

CMMI has its origin in the philosophy and content of the CMM^® for Software (SW-CMM) which was developed in the early 1990's at Carnegie Mellon University. The idea of an evolutionary model for software process improvement was captured first in the SW-CMM. Its current Version 1.1, published in 1993, has been used by thousands of organizations as a basis for improving their application development processes.

As organizations used the SW-CMM, many wanted to extend its principles to other groups within the organization such as systems engineering, business analysts, architecture teams, and even hardware engineering. The organizations needed a collection of best practices and a consistent improvement approach that could span more than just software. Often, they needed to build systems using integrated project teams with members from different disciplines and/or organizations. Nearly every significant project had some portion of the system or work that was outsourced. To cover these areas, a more comprehensive improvement model was required. CMMI brings such a set of practices together into one collection.