Cleanroom software engineering is a theory-based, team-oriented engine
ering process for developing very high quality software under statisti
cal quality control. The Cleanroom process combines formal methods of
object-based box structure specification and design, function-theoreti
c correctness verification, and statistical usage testing for reliabil
ity certification to produce software approaching zero defects. Manage
ment of the Cleanroom process is based on a life cycle of development
and certification of a pipeline of user-function increments that accum
ulate in the final product. Teams in IBM and other organizations that
use the process are achieving remarkable quality results with high pro
ductivity. A phased implementation of the Cleanroom process enables qu
ality and productivity improvements with an increased control of chang
e. An introductory implementation involves the application of Cleanroo
m principles without the full formality of the process; full implement
ation involves the comprehensive use of formal Cleanroom methods; and
advanced implementation optimizes the process through additional forma
l methods, reuse, and continual improvement. The AOEXPERT/MVS(TM) proj
ect, the largest IBM Cleanroom effort to date, successfully applied an
introductory level of implementation. This paper presents both the im
plementation strategy and the project results.