This study extends and makes unique methodological contributions to research on the impact of learning communities (LCs) on community college students. Much of the previous research was short-term, lacked adequate comparison groups, and focused on four-year college students. This four-year study controlled for instructor-related variables by comparing academic outcomes of LC students with those of non-LC students taught by the same instructor during the same semester. Differences in grades, attrition, and retention were compared between students enrolled in two pairs of linked English 101 and Psychology 101 LC classes and students enrolled in non-LC courses with the same professor. Student enrollment in the LC courses was associated with higher grade point averages, lower course attrition rates, and higher fall-to-spring semester retention rates. Reasons for the relative scarcity of LCs in community colleges is discussed, along with recommendations as to how institutions can encourage the growth of LCs on their campuses.