The development of the Computer Assisted Testing (CAT) System at the University of Delaware is described. The introduction presents the background leading up to interactive terminal testing in 1973. Documentation for the system includes CAT System programs, format of questions for constructing test item pools, format for entering class lists, testing conditions for terminal tests, sample hard copy test, sample student record, sample anonymous student suggestions, and sample item analysis report. Results of using the CAT System are mentioned briefly. (VT)