This project aims to provide evidence on the effects of vertical integration between hospitals and providers on competition. First, the researchers will document trends in hospital-provider acquisitions in Massachusetts from 2014–2018 with descriptive characteristics of acquired physicians and acquiring hospitals. Then they will estimate the effects on hospital referral patterns, the subsequent impact of changed referral patterns on competition and hospital-insurer bargaining, and ultimately prices. Next, the researchers will examine the impacts of consolidation on provider efficiencies or incentives for hospitals to invest in clinical quality. They also will conduct policy simulations on policy interventions that block mergers, expand referral choice, or cap hospital prices to assess the impact on acquisitions, referrals, prices, and quality. Datasets include the Massachusetts All Payer Claims Database; the Medicare Inpatient, Outpatient, and Carrier files; provider data from the Massachusetts Health Policy Commission; the American Hospital Association Surveys; and Centers for Medicare and Medicaid Services Cost reports, all from 2014–2018.