This study investigated the effects of learning communities on the educational development of first-year college students at a large, urban, highly selective, research university. These communities, known as "clusters," comprised a year long sequence of theme-oriented courses that were team taught and that included interdisciplinary lectures and small seminars. This study sought to understand how learning communities may help foster students' cognitive abilities. Surveys administered during the fall and spring of the first college year determined that cluster participation was significantly and positively associated with all four cognitive outcomes: critical thinking, analytical thinking/problem solving, reading skills, and writing skills. (Contains 5 tables and 2 figures.)