This study investigated (1) the extent to which thinking and problem-solving of fifth-grade students could be improved by the use of self-instructional programed lessons (the productive thinking program), (2) the relationship between productive thinking abilities and IQ-sex characteristics of the learner, and (3) the relationship between level of productive thinking performance and the extent to which overall classroom environment was judged to facilitate creative thinking. Results from 44 fifth-grade classes in Racine, Wisconsin, involving a total of 704 students, showed statistically significant increments in thinking and problem-solving performance on a wide variety of productive thinking measures. These instructional benefits occurred for virtually all types of students, regardless of sex or general IQ level, and were especially marked for students in classrooms having environments which were judged to provide relatively little support and encouragement for the development of productive thinking. Apart from the effects of the instructional materials, performance on the productive thinking measures used in this study was significantly related to sex (girls generally scored higher than boys) and showed a strong and positive relation to IQ. EA 001 340 is a related document. (Authors/JK)