We use panel data on Florida high school students to examine race, poverty, and gender disparities in advanced course-taking. While white students are more likely to take advanced courses than black and Hispanic students, these disparities are eliminated when we condition on observable pre-high school characteristics. In fact, black and Hispanic students are more likely than observably similar white students to take advanced courses. Controlling for students' pre-high school characteristics substantially reduces poverty gaps, modestly reduces Asian-white gaps, and makes little dent in female-male gaps. Black and Hispanic students attend high schools that increase their likelihood of taking advanced courses relative to observably similar white students; this advantage is largely driven by minorities disproportionately attending magnet schools. Finally, recent federal and state efforts aimed at increasing access to advanced courses to poor and minority students appear to have succeeded in raising the share of students who take advanced courses from 2003 to 2006. However, secular trends (or spillovers of the policies to non-poor, non-minority students) have spurred faster growth for other students, contributing to widening demographic gaps in these years. (Contains 17 tables and 24 footnotes.)