David E. Peercy summarizes and explains his more than 20 years of risk assessment work on software maintenance, including an analysis of more than 80 major systems. He places software maintenance in a larger context of software support and integrated logistic support, and describes the process of risk assessment, He contrasts his view of risk with common governmental, management and auditing views, and with the positions of others in the field, Drawing upon his findings and experience, he closes with four major insights about software maintenance, emphasizing the importance for an organization of having supportable software. (C) 1997 by John Wiley & Sons, Ltd.