This paper presents results from a rigorous random assignment study of Learning Communities programs operated at three of six community colleges participating in the National Center for Postsecondary Research's (NCPR) Learning Communities Demonstration. The demonstration's focus is on determining whether Learning Communities are an effective strategy for helping students who have been referred to developmental education. The setting of this research is Hillsborough Community College, Queensborough Community College and Houston Community College. Findings from these three Learning Communities Demonstration sites are as follows: (1) Hillsborough's fairly basic Learning Communities' model did not have a meaningful impact on students' academic success (in terms of likelihood of completing developmental reading, average total credits attempted/earned, and rates of persistence); (2) Both Houston's and Queensborough's Learning Communities programs showed evidence of helping students progress through the developmental math sequence more quickly; and (3) Houston's and Queensborough's Learning Communities programs both did not show evidence of lasting impacts on credit accumulation or retention. (Contains 2 tables.)