The focus of this study was upon the development and evaluation of a computer-assisted branched test to be used in making instructional decisions for individuals in the program of Individually Prescribed Instruction. A Branched Test is one in which the presentation of test items is contingent upon the previous responses of the examinee. The problem was to develop a procedure for this kind of testing for an elementary school mathematics curriculum. Related research was reviewed and a branched test was designed and administered and its hierarchy validated. It was felt that test results must be better related to the curriculum than they now are, but when properly integrated the branched test is more effective in diagnosing individual achievement levels and problem areas than are most conventional tests. Despite the initial hardware costs, the computer's storage and retrieval capacity caused the author to feel that computer-assisted branched testing could be a substantial element of a computer managed instructional environment which permits experimentation with optimizing the integration of information collection, computer testing, and instruction. Bibliography, appendices, tables, and figures are included. (SH)