Between 1985 and 1989, the Student Teacher Achievement Ratio (STAR) Project studied the effect of class size on student achievement in Tennessee schools. The study examined: (1) small classes of 15 students per teacher; (2) regular classes of 24 students per teacher; and (3) regular classes with a teacher's aide. The sample included students from kindergarten through third grade at inner-city, rural, urban, and suburban schools. Results showed achievement benefits for students from small classes over students from the other classes. A Lasting Benefits Study (LBS) was undertaken to determine whether these gains were maintained at the end of students' participation in regular size fourth-grade classes. This report discusses the LBS findings. A battery of tests was administered to 4,320 fourth-grade students who had been in a Project STAR class during third grade. Achievement in reading, language, math, science, study skills, and social science was assessed. For all achievement measures and all school location types, fourth-grade students who had been in project STAR small classes during third grade showed significant advantages over Project STAR students from the other two class-size conditions. Appendixes include definitions of the school types and tables of test scores. Six references are cited. (BC)