The Assessment Resource Center (ARC) at Florida State University provides computer assisted testing (CAT) for approximately 4,000 students each term. Computer capabilities permit a small proctoring staff to administer tests simultaneously to large numbers of students. Programs provide immediate feedback for students and generate a variety of reports for instructors. Courses using the ARC for testing are required to provide an optional retest opportunity for students. Course objectives, test items, and related instructional materials have been developed by teams of instructors with an expert in testing and instructional development. The ARC experience has identified three measurement and two instructional design considerations crucial to the effectiveness of CAT operations in instructional environments: test quality; confidence in mastery decisions; maintenance of test validity; the quality of instructional objectives; and extended feedback following testing. The lack of effective methods to clarify test-identified learning deficiencies is the greatest weakness in the present ARC operation. Guidelines for producing and evaluating instructional objectives, test questions, and remediation procedures should be a central component of future CAT software documentation. Inappropriate computer applications to testing will have unfavorable effects on both the quality of instruction and the perceived benefits of educational measurement. (BS)