Background New payments from Medicare encourage behavioral health services to be integrated into primary care practice activities. Objective To evaluate the financial impact for primary care practices of integrating behavioral health services. Design Microsimulation model. Participants We simulated patients and providers at federally qualified health centers (FQHCs), non-FQHCs in urban and rural high-poverty areas, and practices outside of high-poverty areas surveyed by the National Association of Community Health Centers, National Ambulatory Medical Care Survey, National Health and Nutrition Examination Survey, and National Health Interview Survey. Interventions A collaborative care model (CoCM), involving telephone-based follow-up from a behaviorist care manager, or a primary care behaviorist model (PCBM), involving an in-clinic behaviorist. Main Measures Net revenue change per full-time physician. Key Results When behavioral health integration services were offered only to Medicare patients, net revenue was higher under CoCM (averaging $25,026 per MD in year 1 and $28,548/year in subsequent years) than PCBM (−$7052 in year 1 and -$3706/year in subsequent years). When behavioral health integration services were offered to all patients and were reimbursed by Medicare and private payers, only practices adopting the CoCM approach consistently gained net revenues. The outcomes of the model were sensitive to rates of patient referral acceptance, presentation, and therapy completion, but the CoCM approach remained consistently financially viable whereas PCBM would not be in the long-run across practice types. Conclusions New Medicare payments may offer financial viability for primary care practices to integrate behavioral health services, but this viability depends on the approach toward care integration.