Capability Maturity Model (CMM) had an enormous impact on the practice of software engineering. There is now substantial evidence of the business benefits of CMM-based software and a growing understanding of the factors that contribute to a successful improvement effort. CMM was intended to be a coherent, ordered set of incremental improvements, all having experienced success in the field, packaged into a roadmap that showed how effective practices could be built on one another in a logical progression. CMM has spread far beyond its origins in military avionics applications, and is now used by major organizations in every sector of the economy around the globe. It is sometimes claimed that adopting the CMM encourages too much bureaucracy, or that the CMM is incomplete or flawed. This debate is partly concerned with scope, policy issues and conceptual questions. But the debate also focuses on the supposed consequences of adopting the CMM as the basis for software process improvement efforts. This article presents the results to date of the Software Engineering Institute's efforts to test critical claims and assertions about the CMM. INSETS: The Capability Maturity Model for Software.;Adoption of the CMM: A Growing Phenomenon..