We interviewed hospitalist and nonhospitalist respondents as part of the Community Tracking Study site visits to examine how the growing use of hospitalists has affected care delivery systems. The growth of hospitalist programs contributes to a loss of physicians' participation on hospital medical staffs, which increases the burden of coordination and blurs accountability for the quality of postdischarge care. Arrangements where companies and multispecialty medical groups employ hospitalists are more likely than others to establish routines for ensuring coordinated transitions upon hospital admission and discharge. Policymakers could support the development of guiding principles for care coordination, greater reliance on nonphysicians, and reintegration of inpatient and outpatient providers.