The authors analyze national data on recent college matriculants to investigate gender and racial/ethnic disparities in STEM fields, with an eye toward the role of academic preparation and attitudes in shaping such disparities. Results indicate that physical science/engineering (PS/E) majors are dominated by men, but not, however, disproportionately by White men. After accounting for high school preparation, the odds of declaring a PS/E major are two times greater for Black males than for White males, and Black females are closer than White females to closing the gap with White males. The authors find virtually no evidence that math attitudes contribute to disparities in choice of a PS/E major. Finally, in contrast to PS/E fields, biological sciences draw relatively equitably from all groups. (Contains 6 notes, 1 table, and 3 figures.)