A great number of students, and a particularly high proportion of females, do not study mathematics beyond minimum high school requirements. Research indicates that segregation of mathematics classes may help reduce the incidence of female students dropping out of that subject. In an attempt to redress this situation, A. Y. Jackson Secondary School of North York, Ontario, elected to stream all grade 10 advanced mathematics classes by sex, beginning in 1984. This study evaluated the effects of the segregated classes on participation rates by sex, student attitudes, student achievement, and reactions of students, parents and teachers. The study was designed to be conducted over a 4-year period, so that the progress of the students could be monitored through grades 10-13. The results of the first year study showed that there may have been some changes in the attitude of certain students, and there may have been some changes in the achievement of some students. The largest percentage of comments made by parents and students reflected the belief that attitudes and achievement were not affected by segregated classes. Teachers were positive about the program. Appendices include a literature review and bibliography of three pages, and student and parent questionnaires. (JAZ)