ABSTRACT: OBJECTIVE: To identify primary care practice characteristics associated with colorectal cancer (CRC) screening performance, controlling for patient-level factors. DATA SOURCES/STUDY SETTING: Primary care director survey (1999-2000) of 155 VA primary care clinics linked with 38,818 eligible patients' sociodemographics, utilization, and CRC screening experience using centralized administrative and chart-review data (2001). STUDY DESIGN: Practices were characterized by degrees of centralization (e.g., authority over operations, staffing, outside-practice influence); resources (e.g., sufficiency of nonphysician staffing, space, clinical support arrangements); and complexity (e.g., facility size, academic status, managed care penetration), adjusting for patient-level covariates and contextual factors. DATA COLLECTION/EXTRACTION METHODS: Chart-based evidence of CRC screening through direct colonoscopy, sigmoidoscopy, or consecutive fecal occult blood tests, eliminating cases with documented histories of CRC, polyps, or inflammatory bowel disease. PRINCIPAL FINDINGS: After adjusting for sociodemographic characteristics and health care utilization, patients were significantly more likely to be screened for CRC if their primary care practices had greater autonomy over the internal structure of care delivery (p<.04), more clinical support arrangements (p<.03), and smaller size (p<.001). CONCLUSIONS: Deficits in primary care clinical support arrangements and local autonomy over operational management and referral procedures are associated with significantly lower CRC screening performance. Competition with hospital resource demands may impinge on the degree of internal organization of their affiliated primary care practices.