Two of the most fundamental ways in which cells and animals interact with their environment are through obtaining nutrients sufficient to sustain life and defending against attack of potentially pathogenic organisms. It is not surprising with some reflection, therefore, that immune cell metabolism and function are linked and that the immune system as a whole is connected and closely interacts with basic metabolic tissues and processes. This basic premise is now well accepted, but, until recently, was overlooked in both studies of the immune system and in studies of nutrition and metabolism. It had been apparent nearly one hundred years ago, however, that nutrition and immunological state could be associated, as malnutrition was clearly defined as an immunosuppressive condition, with increased infections in poorly fed populations (1, 2). Evolutionarily, it appears that the highly energy-dependent process of immune protection was simply selected as a system to be quickly sacrificed in times of famine, so as to maintain enough energy for immediately vital functions, such as neuronal and cardiovascular systems. This nutrition and immunity association now provides context for the rise of immunometabolism as a field. Current thinking acknowledges that the links between immunity and metabolism are not limited to malnutrition and include basic cellular processes as well as close interactions between immune cells and metabolic tissues. In particular, immune responses are highly energy dependent, and how lymphocytes obtain their energy offers a new approach to modify immunity and define specific immune functions. Metabolic stress response pathways, such as autophagy, are also intimately tied to immunity, to activate the innate immune response, to allow adaptive immunity, as well as to directly eliminate some pathogens. In addition, the growing incidence of obesity and the metabolic syndrome in the western world are now known to have inflammation and overactive immunity as a root source of pathology. As recognition of the importance of these areas grows, the field of immunometabolism is now of broad importance in basic biologic understanding of immunity as well as in a variety of pathological settings. This volume includes reviews to discuss current literature and thought on each of these topics and to point toward future directions how metabolic links with immunity ultimately may be exploited to treat a wide array of metabolic and immunologic diseases.