Formative and non-formative evaluation are examined from the viewpoints of adaptation to improve individual performance and maintenance to preserve an existing system. Distinctions are made in terms of the experimental method, criterion-referenced measures, accessible events, and individual behavior. The functions of other distinguishing features are also examined, such as the quantification of weak and indirect variables for active maintenance. A case is made for the advantages and disadvantages of both types of evaluations. An increased role for formative evaluation is advocated as well as a deliberate rather than an “accidental” use of non-formative evaluation.