A description and evaluation are given of the Individualized Mathematics (IM) program. IM is an outgrowth of the work of the Learning Research and Development Center (LRDC) at the University of Pittsburgh. The program has developed and implemented manipulative lessons for primary grade (K-3) students. Like other LRDC programs, this one includes such components as specific instructional objectives, lesson materials to teach each objective, a testing program for monitoring pupil progress, and specific procedures for using these components in the individualized instruction. The emphasis in this program is on the use of manipulative materials for lessons in which the students have a high degree of self-management. The results of two years of development and investigation showed that the program (1) was manageable, (2) permitted independent study, (3) facilitated pupil progress, (4) produced desired achievement test results, and (5) needed modification to make costs and storage requirements more feasible. (JP)