The Peer-Assisted Learning (PAL) program at the University of Minnesota has drawn from the best practices of Supplemental Instruction, Peer-Led Team Learning, Structured Learning Assistance, the Emerging Scholars Program, and other successful postsecondary peer cooperative learning models to establish guiding principles for structuring learning sessions. To estimate the impact attending weekly math PAL sessions has on students’ chances of successful course completion, an observational study was conducted fall 2008 of 534 University of Minnesota students enrolled in two undergraduate math courses. Success was defined as passing the class with a C- or above, and failure as receiving a D+ or below, including withdrawals. In addition to PAL attendance, 16 other factors were considered in this analysis. Attending all PAL sessions during the semester corresponded with ten times higher odds of success than attending none. While further experimental studies are needed, these observations suggest that following these guiding principles result in effective peer cooperative learning sessions.