Recent studies have revealed dramatic differences among academic medical centers (AMCs) in the quantity of care provided to their patients. The implications, however, depend upon whether the additional resources provided by some centers lead to better results. This study describes the content, quality, and outcomes of care across AMCs that differ by up to 60 percent in the overall intensity of medical services delivered to patients with serious chronic illnesses. Efforts to reduce costs will require attention to supply-sensitive services (the frequency of hospital stays, physician visits, specialist consultations, diagnostic tests, and minor procedures) and should include a focus on the longitudinal efficiency of hospitals and medical staffs.