In the validation of automated systems for the pharmaceutical and health care industries, assurance of compliance with applicable regulations is accomplished through a well designed validation program. The program must be designed to provide documented evidence that automated systems (hardware and software) have done, are doing, and/or will do, reliably, what they are supposed to do--the key word in this statement being “documented.” The documentation requirements for automated, particularly “paperless” systems, can be a formidable obstacle to validation; however, if a modular, or life-cycle, approach (qualification of the component parts followed by qualification of the integrated system) is used the task becomes manageable. One approach we have found in our experience to successfully generate, evaluate, and manage the documentation required for validation of automated systems is the use of a Quality Plan. This approach has also proved invaluable in defining the system, the first step in any life-cycle approach to validation of an automated system. The following discussion outlines the Quality Plan approach to validation of computer systems, and focuses on system definition because of its importance as the basis for both the design and testing of these systems and associated software. Although the discussion addresses systems used primarily in the pharmaceutical and health care industries, the Quality Plan concept is applicable to any system that must function reliably and with documented performance.