The growth in medical imaging over the past 2 decades has yielded unarguable benefits to patients in terms of longer lives of higher quality. This growth reflects new technologies and applications, including high-tech services such as multisection computed tomography (CT), magnetic resonance (MR) imaging, and positron emission tomography (PET). Some part of the growth, however, can be attributed to the overutilization of imaging services. This report examines the causes of the overutilization of imaging and identifies ways of addressing the causes so that overutilization can be reduced. In August 2009, the American Board of Radiology Foundation hosted a 2-day summit to discuss the causes and effects of the overutilization of imaging. More than 60 organizations were represented at the meeting, including health care accreditation and certification entities, foundations, government agencies, hospital and health systems, insurers, medical societies, health care quality consortia, and standards and regulatory agencies. Key forces influencing overutilization were identified. These include the payment mechanisms and financial incentives in the U.S. health care system; the practice behavior of referring physicians; self-referral, including referral for additional radiologic examinations; defensive medicine; missed educational opportunities when inappropriate procedures are requested; patient expectations; and duplicate imaging studies. Summit participants suggested several areas for improvement to reduce overutilization, including a national collaborative effort to develop evidence-based appropriateness criteria for imaging; greater use of practice guidelines in requesting and conducting imaging studies; decision support at point of care; education of referring physicians, patients, and the public; accreditation of imaging facilities; management of self-referral and defensive medicine; and payment reform.