This paper is concerned with defining evaluation as a domain in instructional technology, and with specifying the sub-areas of the domain. In education, evaluation is the process of determining the adequacy of instruction. It begins with problem analysis, which refers to determining the nature of the solution and the parameters of the problem. A second major area of evaluation is criterion-referenced measurement, which refers to determining mastery. Criterion-referenced measures, which are sometimes tests, measure the extent to which the learner has met the objective. The last subdomains are represented by formative and summative evaluation. Formative evaluation refers to gathering information on adequacy and using this as a basis for further development. Summative evaluation refers to gathering information and using it to make decisions about utilization. Needs assessments and other types of front-end analyses have been primarily behavioral in orientation, but the current stress on the impact of context on learning is giving a cognitive, and at times constructivist, orientation to the needs assessment process. The performance technology movement is making an important contribution to this process. Another area of great interest is the measurement of higher level cognitive, affective, and psychomotor objectives. Several recent perspectives on evaluation are reviewed. (Contains 31 references.) (SLD)