The study, involving 119 academically handicapped third, fourth, and fifth graders, examined the effects of an instructional method (Team-Assisted Individualization) that combines cooperative learning with individualized learning in mathematics. Previous studies have found that the use of cooperative learning instructional processes can improve relations between normal-progress students and mainstreamed handicapped students; however, these processes incorporate class-paced instruction, which is generally not appropriate for handicapped students. Principal components of the Team-Assisted Individualization Program (TAI) were four- or five-member teams each with high, average, and low achievers; presentation of a diagnostic test at the beginning of the project on mathematics operations; individualized curriculum materials covering addition, subtraction, multiplication, division, numeration, decimals, fractions, and word problems; the team study method; team scores and team recognition; and teacher review sessions. A materials-only (MO) group used the same curriculum materials and procedures as the TAI group except the students worked individually and did not receive team scores or certificates. The control group used traditional methods for teaching mathematics. Ss were evaluated on sociometric measures, mathematics achievement, attitudes, and behavior ratings. Results confirmed the hypothesis that the cooperative individualized program for mathematics instruction (TAI) would increase the sociometric status of mainstreamed academically handicapped students. However, it appeared that the use of cooperation per se may not have been the critical component of the program, because the mainstreamed students in the groups using individualized curriculum materials only also improved significantly in sociometric status. (SW)