This study examined academic differences between students who attended 21st Century Community Learning Center (CCLC) programs frequently (60 or more days) and matched nonattendees during the 2008-2009 school year. Schools included in the study represented only those centers found to be implementing high-quality programming, as measured by a strenuous site visit process in Indiana. Significant interactions between program attendance and fall academic achievement predicted performance on the spring tests in both math and reading. Simple effects were only shown for math, in which program attendees who failed the test in the fall scored higher than non-participants. Implications for practice and future research are discussed. (Contains 7 tables and 2 figures.)