Background/Context: Underprepared students at community colleges are often assigned to a sequence of developmental education courses that can substantially delay, or even halt, their progress to degree completion. In 2014, Florida implemented a comprehensive reform under Senate Bill (SB) 1720 that allowed the majority of incoming students to enroll directly into college-level courses, while remaining developmental education courses were offered in new instructional modalities that were designed to be completed more quickly than traditional semester-long courses. Colleges provided extensive advising and academic support services intended to help students succeed while progressing at a more accelerated pace. Purpose/Objective/Research Question/Focus of Study: In this study, we examined the impact of Florida's developmental education reform on early momentum. More specifically, we defined early momentum as student success in early outcomes (such as the number of credits attempted and earned), which may set students on a promising long-term trajectory on subsequent postsecondary outcomes. Population/Participants/Subjects: Our sample included all first-time-in-college students enrolled in all 28 public state colleges. We included three cohorts of students before the reform and up to three cohorts of students after the reform. Each cohort consisted of approximately 70,000 students. Research Design: We used an interrupted time series design to compare student outcomes three years before the reform with those up to three years after the reform. Our outcome variables, measured one and three years following initial college enrollment, represented continuous indicators for the number of college-level credits attempted and the number of college-level credits earned. We also examined whether the data revealed heterogeneity in the reform's impacts by race/ethnicity, family income status, and level of high school academic preparation. Findings/Results: We found small positive effects on all outcomes, indicating that the reform accelerated student success in both the short term and longer term. The impacts of the reform were even greater for Black, Hispanic, Indigenous, low-income, and underprepared students (particularly in the first year), thus reducing existing achievement gaps. Conclusions/Recommendations: Florida's SB 1720 consisted of a complementary set of reform efforts that may together have a larger impact than any single component alone. The results suggest that initial momentum gains in the first year may have set some students on a more successful long-term trajectory, particularly those most likely to be assigned to developmental education before the reform. Colleges should continue to provide comprehensive student support services to help students succeed while progressing at a more accelerated pace. [For the corresponding grantee submission, see ED610561.]