It was postulated that the combination of heterogeneity and an element of similarity--i.e., complementarity--would produce a stimulating yet cohesive group interaction. The subjects for this study were 359 students enrolled in six required English and six required social science classes at Miami-Dade Community College. Within the limitations of the study, the following conclusions seem warranted: assignment to small groups on the basis of complementary personality types as identified by the Myers-Briggs Type Indicator does lead to greater growth in critical thinking, openmindedness, and tolerance of ambiguity than does assignment on the basis of either heterogeneity or randomness; assignment on the basis of heterogeneity is conducive to greater growth in critical thinking and tolerance of ambiguity than is random assignment, although heterogeneous grouping does not appear to facilitate openmindedness or the verbal aspect of creativity. Assignment of students to small groups on the basis of complementarity seems to be more effective than the haphazard assignment methods frequently used in college classes. (Author/RB)