The purpose of this study is to identify the policies and practices of community colleges that are effective in enabling their students to succeed in postsecondary education. The study was conducted through a partnership with the Florida Department of Education's Division of Community Colleges and Workforce Education and funded by the Lumina Foundation for Education as part of its Achieving the Dream initiative. Achieving the Dream is a national effort to increase the success of community college students, particularly those in groups that have been underserved in higher education. The initiative works on multiple fronts including technical assistance to community colleges, research, public engagement, and public policy-and emphasizes the use of data to drive change. This study builds on earlier research that the Community College Research Center (CCRC) has conducted using national survey data. Transcript-level data on 150,000 students in three cohorts of first-time Florida community college students and a regression methodology to estimate the effect that each of the 28 Florida community colleges has on the probability of its students' achieving a successful outcome, after controlling for characteristics of the individual students was used. This effect can be seen as a measure of value added-the impact that a college has on its students' educational success independent of the characteristics of individual students. The colleges according to their estimated effects on student success, were then ranked. Appended are: (1) Methodology for Measuring Institutional Impact on Student Success Using Student Cohort Data from the Florida Community Colleges; and (2) Profiles of High- and Low-Impact Community Colleges. (Contains 4 tables and 27 endnotes.) [This report was written with Thomas R. Bailey, Peter Crosta, Timothy Leinbach, James Marshall, Andrea Soonachan, and Michelle Van Noy.]