This study explores whether students from low-income families and racial/ethnic minority groups have the opportunity to benefit in what is arguably the most rigorous type of credit-based transition program: the International Baccalaureate Diploma Programme (IBDP). The analyses first describe national longitudinal trends in characteristics of schools offering the IBDP and the characteristics of students within schools who enroll. The analyses draw on data from the International Baccalaureate database, which include individual-level data on more than 400,000 IBDP students from 1995 through 2009, as well as data from the Common Core of Data from the National Center for Education Statistics. The article also draws on data collected from a survey of IBDPs in Florida to document variations in the opportunity to benefit from available IBDPs.