This investigation was undertaken to compare males and females on their performance on standardized mathematics achievement tests during primary grades. The achievement of more than 3,000 children in grades one through three was measured in the five school districts in which the University of Georgia Follow-Through Program was implemented. The 1978 Metropolitan Achievement Test (MAT), Form JS, Survey Battery was administered to all Follow-Through pupils on a Fall (pre-test) and Spring (post-test) basis for the 1978-79 and 1979-80 school years. The results of the analyses of the mathematics achievement data indicated several possibilities which seem to warrant further research. Among the hypothetical postulates generated: (1) During grades one and two, females from disadvantaged populations scored higher than males in numerical operations and concepts as reflected in standardized tests; (2) Summer loss in mathematics achievement may be attributed to environmental factors in the disadvantaged children's communities; and (3) Understanding of mathematical operations and concepts is a function of cognitive development in young children. (MP)