This action research project examined the impact of a program for improving age-inappropriate behaviors that interfere with personal and academic progress. A total of 69 students from 3 elementary classrooms and 2 speech therapy groups were involved in the research. The targeted population consisted of fourth and sixth graders; students with autism in a self-contained classroom; and 3- through 12-year-olds with moderate mental retardation in a self-contained building, all in central Illinois communities. Inappropriate classroom behavior related to listening, on-task behavior, cooperative learning, and aggression was documented through teacher check lists, parent and teacher surveys, teacher anecdotal notes, teacher and student journals, test scores, and progress toward Individual Educational Plan goals. The intervention consisted of: (1) a parental involvement program; (2) a direct instruction social skills program; (3) a cooperative learning program implemented through curricular units; and (4) modeling and reinforcing appropriate behaviors to reduce aggression. The social skills and cooperative learning programs were implemented through 18 weeks of direct instruction to mixed gender groups of 4 to 6 students. Sessions were conducted twice a week for 20 to 40 minutes each. Cooperative learning activities were implemented in reading, science, social studies, or language arts, depending on the grade. The parental involvement program consisted of curriculum-based take-home activities and a newsletter for the regular education students and weekly "suitcase" activities for special education classrooms. Post-intervention data indicated an increase in age-appropriate behaviors and enhanced academic performance. (Appended are data collection and classroom materials and raw data. Contains 17 references.) (KB)