We show how metrics that are collected and validated during development can be used during maintenance to control quality and prioritize maintenance work. Our approach is to capitalize on knowledge acquired and experience gained with the software during development through measurement. The motivation for this research stems from the need to provide maintenance management with the following: 1) quantitative basis for establishing quality objectives during maintenance and 2) rationale for allocating resources - people, money, and equipment - to maintenance tasks. We base our approach on validating selected metrics against related quality factors during development and using the validated metrics duringmaintenance to: 1) establish initial quality objectives and quality control criteria and 2) prioritize software components (e.g., module) and allocate resources to maintain them. We use the validity criteria discriminative power and tracking to illustrate the process.