This study examined participation in accelerated college credit programs dual enrollment, concurrent enrollment, and Advanced Placement courses in Rhode Island high schools to understand their effects on educational attainment in the 2013/14 grade 9 cohort. The state, which has funded and promoted these opportunities for students to earn college credit during high school over the past five years, sought evidence of the programs' effects on participants' high school graduation rates, postsecondary enrollment rates, and enrollment rates in developmental education courses in college. The study found that male, economically disadvantaged, and racial/ethnic minority students were underrepresented in accelerated college credit programs. Participation in these programs had positive effects on students' rates of high school graduation and postsecondary enrollment. Among students in the cohort who enrolled in Rhode Island public colleges, participation was associated with lower rates of developmental education course enrollment in the first year of college. The effects of participating in an accelerated college credit program were similar for economically disadvantaged students and for their peers. [For the Study Snapshot, see ED612888. For the appendices, see ED612890.]