This is the first national report to look at how effectively communities and hospitals coordinate care for some of their sickest patients—those leaving the hospital after a stay to treat an acute or chronic illness. Without high-quality care coordination, patients can bounce from home to the emergency room and back into the hospital, sometimes repeatedly. The readmission rate to hospital is increasingly seen as a marker of a local health care system’s ability to coordinate care for patients across the full continuum of care settings: hospitals, rehabilitation and skilled nursing facilities, nursing homes, clinician offices, hospice and home. Better care coordination promises to reduce readmission rates and improve patients’ lives while reducing costs.