This study aims to develop and validate modules that can be used in teaching the course Theories of Personality. It consists of a comprehensive coverage of twenty of the most influential theories. R. M. Gagne's ("1988, 1996) instructional theory on the nine events of instruction served as the framework of this study. Survey results showed that the developed modules are valid in content, suitability, clarity, usefulness and adequacy. The quasi-experimental design and the use oft-test for the 5 representative instructional modules that were tested showed the effectiveness of modular instruction in enhancing knowledge, skills and attitudes of the participants in the pilot study.