This article summarizes data on the relationship between obesity and depression in the population. Both obesity and depression are increasingly prevalent and associated with numerous health complications including hypertension, coronary heart disease, and increased mortality. There does not appear to be a simple or single association between these disorders. Meta-analytic studies suggest no statistically significant relationship, although pooling all subjects may mask important variables that moderate or mediate potential covariations. Sociodemographic, psychosocial, and genetic factors may render certain obese individuals more prone to depression or vice versa. Physiological and behavioral variables that link obesity and depression have received limited study. There are likely multiple obesity-depression covariations in the population, rather than a single pattern of association. There is a need for longitudinal and mechanistic studies to understand casual pathways and greater collaboration between depression and obesity specialists.