The purpose of the study was to assess the relative mathematics achievement of English-speaking pupils enrolled in grades 3, 6, and 9 in regular English or French immersion programs during the 1981-82 and 1982-83 school years. The data were obtained as part of a 2-year evaluation of a system-based mathematics program developed by an Ontario school board. For grade 3, eight English program and four French immersion classes were selected for each year. For grade 6, the 1981-82 sample consisted of 12 English program classes and the 1982-83 sample consisted of six English program and four French immersion classes. For grade 9, the 1981-82 sample consisted of 12 English program classes, and the 1982-83 sample consisted of 10 English program and two French immersion classes. Most differences between English program and French immersion pupils were small and nonsignificant in grade 3. Results for grades 6 and 9 suggested that the French immersion pupils had comparable or superior mathematics scores than their English program peers. (MNS)