This entry provides an overview of current knowledge and thinking about the nature, causes, and consequences of food insecurity as well as information about the major policies and programs aimed at alleviating food insecurity in the United States. Food insecurity is considered at the nexus of person and environment, with discussion focusing on the biological, psychological, social, and economic factors that are interwoven with people’s access to and utilization of food. The diversity of experiences of food insecurity is addressed, with attention to issues of age, gender, culture, and community context. Finally, implications for social work professionals are suggested.