This study examines the organizational and institutional factors that may be associated with the success of schools of social work (SOSWs) in securing research grant awards from the National Institutes of Health (NIH) and constituent agencies. Using data from the CRISP database on NIH grant funding, the Lombardi Program on Measuring University Performance, the Council on Social Work Education, the American Association of University Professors, and other sources, several key factors were identified as being associated with SOSWs' grant success: having a PhD program, not having a BSW program, being an independent academic unit, faculty publication rates, having a medical school in the home university, having higher faculty salaries in the home university, and the home university's overall grant success. The principle of "accumulative advantage" describes relative grant success well: During 1993-2005, only 13 SOSWs accounted for almost 75% of all NIH grants awarded to SOSWs. (Contains 3 tables and 3 figures.)