This report describes a program for implementing specific cooperative grouping patterns in order to increase students' academic performance. The targeted population consisted of junior high and high school students located in the northwest and southwest suburbs of a large metropolitan area. An instructional strategy in which both like-gender and mixed-gender grouping patterns were used in Spanish and math classroom cooperative activities is outlined. Findings indicate that single-gender groups achieved higher scores, received more favorable evaluations, and generally had more positive group interactions. (Contains 18 references.) (WRM)