The Comprehensive School Mathematics Program (CSMP) is a program of CEMREL, Inc., one of the national educational laboratories, and was funded by the National Institute of Education (NIE). Its major purpose is the development of curriculum materials for the elementary grades. Beginning in 1973, CSMP ran an extended pilot trial of its elementary program. This report summarizes the data collected during its fourth year, with evaluation focusing on third-grade students and teachers. In the fall of 1976, CSMP materials were being used in 13 states and in about 1000 classes ranging from kindergarten to fourth grade. Evaluation here concentrates on the 23 districts and 108 classes using the third-grade materials. Three broad issues were explored: 1) After studying CSMP materials for 3 years, have students learned the computation skills and mathematics concepts usually expected of third graders? 2) Are these CSMP students better able to deal with certain novel mathematical problem situations than they would otherwise have been? and 3) What are the reactions of teachers to the CSMP third-grade materials? (MP)