Primary care clinics from diverse geographic and socioeconomic backgrounds make up NIPC PBRN. Both academic and community-based practices are included. All sites are located within family medicine residency programs (85.4%), internal medicine residency programs (10.4%), or family medicine faculty practices (4.2%). Half (52%) of practices are affiliated with a community hospital and 63% are located in communities with populations <250,000 people. Sixty-one percent of participating practices have 300-599 ambulatory care visits per week. NIPC PBRN clinics serve a mean of 28% African Americans and 18% Hispanics. Payment methods for patients served by the NIPC PBRN network are Medicaid/government (27%), Medicare (24%), private insurance (33%), uninsured (11%), and other (3%). The clinic sample provides an excellent distribution of typical small communities and rural areas that often have underserved populations.