The document summarizes a two-year longitudinal evaluative study of the elementary school social studies curriculum, "Man: A Course of Study" (MACOS), which was compared with other social studies programs. The aims of the study were to examine what MACOS students seemed to learn, what they retained, and how what was learned was different from what they might have learned in other social studies courses. Data were collected from 15 school districts in 11 states. The sample consisted of 57 fifth and sixth grade social studies classes which were exposed to MACOS and 51 comparison classes which were exposed to other social studies curricula. Classes in both groups were predominantly white, non-low income, and taught by teachers with similar amounts of teaching experience. All classes were given pre- and posttests intended to measure achievement and attitude variables, such as interpretation of ethnographic data, interest in problem solving, and reaction to unusual beliefs and customs. Findings indicated that all students tended to learn most about the content of whatever curriculum they were studying and that MACOS classes did not differ significantly in attitudes toward the cultures they had studied. It was concluded that MACOS was interesting to a large number and variety of students and teachers, more effective with sixth grade students than with fifth grade students, and generally equal to other social studies courses in developing inquiry skills and interest in open-ended problems. (Author/DB)