This large-scale evaluation of Indiana's Prime Time, a funding mechanism designed to reduce class size or pupil-teacher ratio (PTR) in grades K-3 examined the academic performance of nearly 11,000 randomly selected third graders on the state mandated standardized achievement test as a function of class size, PTR, and presence of an instructional aid. Data analysis using hierarchical linear modeling (HLM) indicated that student achievement was strongly influenced by socioeconomic status (SES) and race. Larger class size related to better composite and mathematics achievement, particularly in higher SES schools. Similarly, the presence of an instructional assistant predicted better achievement in reading, language, and the composite score only in higher SES schools. Analysis of race and class size showed that black students had better achievement in smaller classes, while white students did better in larger classes. HLM analyses of the student-teacher ratio showed pervasive SES and race effects. Better language, mathematics, and composite achievement was associated with classrooms that had Prime Time Assistants in higher SES schools. Better mathematics, reading, and composite achievement related to classrooms with higher PTR. (Contains 16 tables and 16 references.) (SM)