Background:Hospital-based acute care [emergency department (ED) visits and hospitalizations] that is preventable with high-quality outpatient care contributes to health care system waste and patient harm.Objective:To test the hypothesis that an ED-to-home transitional care intervention reduces hospital-based acute care in chronically ill, older ED visitors.Research Design:Convergent, parallel, mixed-methods design including a randomized controlled trial.Setting:Two diverse Florida EDs.Subjects:Medicare fee-for-service beneficiaries with chronic illness presenting to the ED.Intervention:The Coleman Care Transition Intervention adapted for ED visitors.Measures:The main outcome was hospital-based acute care within 60 days of index ED visit. We also assessed office-based outpatient visits during the same period.Results:The Intervention did not significantly reduce return ED visits or hospitalizations or increase outpatient visits. In those with return ED visits, the Intervention Group was less likely to be hospitalized than the Usual Care Group. Interview themes describe a cycle of hospital-based acute care largely outside patients' control that may be difficult to interrupt with a coaching intervention.Conclusions and Relevance:Structural features of the health care system, including lack of access to timely outpatient care, funnel patients into the ED and hospital admission. Reducing hospital-based acute care requires increased focus on the health care system rather than patients' care-seeking decisions.