This article presents the research findings of an evaluation of the academic impacts of 21st Century Learning Centers (CCLC) in Louisiana. Using quasi-experimental design, the article operationalizes academic achievement as core and subject test performance on nationally standardized pre- and posttests (Iowa Test of Basic Skills; ITBS). Based on previous research and evaluation requirements, the article (a) employs outcomes of interest to policymakers (standardized test scores); (b) uses program attendance as a key independent variable; (c) uses efficient methods to control for extraneous impact on the dependent variable; and (d) focuses the evaluation on a specific group of student--at-risk children in Louisiana. Findings indicate that the 21st CCLC program is having a positive academic impact on participants who attend the program for 30 days or more. Further, impacts are shared across specific grantee programs, specific subjects, and subgroupings of students. Finally, the study finds that intensity of attendance is positively related to academic impact. (Contains 2 figures, 5 tables and 12 footnotes. Overview of Programs is appended.)