A computerized testing system was installed on an experimental basis at the Basic Electricity and Electronics School of the Naval Training Center in San Diego. The system consisted of a network of IBM Personal Computers running a slightly modified version of the commercially available MicroCAT Testing System. It was configured to fit transparently into the school's computer-managed instruction system. After a few minor adjustments and a few added features, the system met its goal of paralleling the paper-and-pencil version of the tests with a minimum of change in standard testing procedures. Now in place, the system provides a base on which diagnostic testing research can begin. Diagnostic testing will be implemented using the custom interface included in MicroCAT, which allows users to link FORTRAN or Pascal procedures to MicroCAT. (Author/JAZ)