Present federal education policies promote learning in science, technology, engineering, and mathematics (STEM) and the participation of minority students in these fields. Using longitudinal data on students in Florida and North Carolina, value-added estimates in mathematics and science are generated to categorize schools into performance levels and identify differences in school STEM measures by performance levels. Several STEM-relevant variables show a significant association with effectiveness in mathematics and science, including STEM teacher turnover, calculus and early algebra participation, and mathematics and science instructional indices created from survey items in the data. Surprisingly, a negative association between students' STEM course participation and success in STEM is consistently documented across both states, in addition to low participation of underrepresented minority students in successful schools in STEM.