Using data from 10 states, Hyde, Lindberg, Linn, Ellis, and Williams (2008) found gender similarities in performance on standardized math tests. The present study attempted to replicate this finding with national data and to extend it by examining whether gender similarities in math performance are moderated by race, socioeconomic status, or math ability in Grades 8, 10, and 12. Data from 9,813 students from the National Education Longitudinal Study (NELS) were used. The current results showed gender similarities in performance on standardized math tests across the three grades examined. Furthermore, this finding was not modified by race, socioeconomic status, or math level. These results provide empirical evidence for teachers and parents to encourage girls to persist and excel in math. (Contains 1 table.)