Across the United States, community colleges offer millions of students an open-access, low-cost postsecondary education. However, of the students who enroll in community college hoping to earn a credential or transfer to a four-year institution, only about half achieve their goal within six years. For students who enter college needing developmental (remedial) education in reading, writing, or math, this rate is even lower. Learning communities, in which cohorts of students enroll in two or more linked courses together, are often employed to improve these students' success. In addition to linking courses, learning communities often incorporate other components, such as faculty collaboration, shared assignments and curricula, and connections to student support services. Merced College in California and The Community College of Baltimore County (CCBC) each developed learning communities designed to boost the academic success of their developmental English students. These colleges are two of the six in the National Center for Postsecondary Research's (NCPR) Learning Communities Demonstration, in which random assignment evaluations are being used to determine the impacts of learning communities on student success. At Merced, learning communities linked developmental English courses with a variety of other courses at the developmental and college levels. At CCBC, learning communities linked developmental English with a range of college-level courses and a weekly one-hour Master Learner session designed to support curricular integration and student learning. The key findings presented in this report are: (1) Both Merced and CCBC implemented relatively advanced learning communities. A strong cohort experience was provided to students, and other aspects of the learning communities model were implemented with variation at each college. On average, the colleges succeeded in providing program group students with an experience that was substantially different from the experience of their control group counterparts; (2) At Merced, learning communities students attempted and earned significantly more developmental English credits than students in the control group during the program semester. At the end of the subsequent semester, they had passed significantly more English courses than their control group counterparts; (3) At CCBC, there were no meaningful impacts on students' credit attempts or progress in developmental English; and (4) On average, neither college's learning communities program had an impact on college registration in the postprogram semester, or on cumulative credits earned. NCPR has now presented findings from all six colleges in the demonstration. They show that when one-semester learning communities have impacts, they tend to be concentrated in the semester in which students are enrolled in the program. The evidence to date suggests that one-semester learning communities programs by themselves are typically not sufficient to boost reenrollment or increase credit accumulation. However, this is not the final report on the demonstration; in 2012, NCPR will release a report that synthesizes the findings across all of the colleges studied and includes an additional semester of student follow-up at each college. Supplementary table and figures are appended. Individual chapters contain footnotes. (Contains 11 tables, 9 figures and 1 box.) [This paper was written with Amanda Grossman. References for the executive summary are included. For "Learning Communities for Students in Developmental English: Impact Studies at Merced College and the Community College of Baltimore County. Executive Summary," see ED529250.]