Secondary school tracking is organized in some countries on a course-by-course basis within schools and in other countries as explicit academic and vocational streaming, often in separate school buildings. This article is the first to compare these two forms of tracking, using student-level tracking data across the United States and 19 other developed countries. Results indicate that course-by-course tracking is less segregated by socioeconomic status (SES) than is academic/vocational streaming. Yet both forms of tracking have comparable achievement gaps between tracks. Among students in the same track, SES disparities in achievement are larger in course-by-course tracking than in academic/vocational streaming.