During the exploratory phase of this two-year project, 234 instructional computer programs were written by 167 junior and senior high school students, instructed as individuals, in small groups, and in whole classes. Then a doctoral study investigated the effectiveness of computer-assisted instruction in the development of problem solving skills. The study compared three conditions of learning from booklets, three conditions of computer training, and one untutored group in each of six eighth grade classes, all crossed on sex and two IQ levels (above and below the class average). Data analysis showed that students below the class IQ average of 113 who used a combination of two types of computer training materials out performed every other group in the three main problem solving functions. A study of paired learners at different IQ levels used the same design as the doctoral study, but no significant results emerged. Negative results were also obtained from another small study which investigated ability changes in seventh grade students following experience in computer programing. Finally, two versions of the language COMPUTEST for the IBM 1620 and a conversational language for use on the IBM 360 remote terminals were developed. The dissertation provides the bulk of this document. (BB)