By allowing students to take college classes and earn college credit while still in high school, credit-based transition programs (CBTPs) may improve student access to college. While policymakers support their expansion, there are currently no theoretical models for guiding CBTP programs. Based on a study of five CBTPs, the authors describe how the programs attempt to meet the needs of a wide range of learners, identifying features that appear to best prepare middle- and low-achieving students for postsecondary success, such as curricular pathways and support services. The authors propose a conceptual model that shows the interrelationship between coursework, support services, knowledge about college, and motivation, and encourage state policies that include support for these components.