Obesity is widespread in the United States and is a risk factor for chronic illness, impaired quality of life, and mortality. While increased rates of obesity are most plausibly attributed to social, economic, and environmental factors, genetic explanations for obesity have often been emphasized. This has occurred in the context of trends in which the conceptualization of obesity as a biomedical disease has been increasingly ascendant in recent years. The proposed research will examine the extent to which primary care providers primarily endorse genetic explanations for obesity and whether such beliefs might be related to a dearth of knowledge about genetics (Aim 1). It will also test how patient variables affect primary care physicians’ likelihood of attributing obesity to genetic causes, and how primary care providers’ endorsement of genetic attributions relates to attitudes toward patients and clinical judgments regarding patient care (Aim 2). In addition, the research will examine how American adults with obesity react to genetic explanations for obesity in healthcare (Aim 3). This latter aim will be accomplished through an experiment testing how U.S. adults with obesity respond to a description of a physician who does (vs. does not) endorse genetic explanations of obesity (Aim 3a), as well as through focus groups in which U.S. adults with obesity will discuss their views about the use of genetics in obesity-related healthcare (Aim 3b). The proposed research will shed light on ethically significant questions related to how beliefs about the role of genetics in obesity may shape clinical care for obesity and physician-patient relationships during this care, with potentially significant implications for health outcomes. It will also inform future efforts to determine how the genetics of obesity can be taught to clinicians and discussed with patients in ways that avoid harming patient care, health outcomes, and the important relationship between patients who have obesity and their healthcare providers.