The coordination of metabolic programs with immune cell fate is a fundamental event in immunity. Immune cells are known for their ability to rapidly transition from resting to activated states in response to external stimuli. Typically, their activation is accompanied by increased expression of large panels of immune effector molecules, and in the case of lymphocytes, is also accompanied by extensive and rapid cellular proliferation. Recent studies have revealed the fundamental importance of metabolic reprogramming, including dynamic regulation of aerobic glycolysis (the Warburg effect), lipid synthesis and degradation, and mitochondrial activity, in immune cell activation and differentiation and the outcome of immune responses. This process depends upon the interplay between the metabolic machinery and immune signaling and transcriptional pathways, and is further shaped by the availability of metabolic substrates and nutrients within the cells and in the microenvironment, including those produced by microbiota. The critical link between metabolism and immunity is indicated by findings that aberrant immune cell metabolism not only affects inflammatory responses and adaptive immunity, but also contributes to metabolic disorders. The goal of this Keystone Symposia meeting is to bring together leading investigators working on metabolism (organismal, cellular, and microbial metabolism) and immunobiology. Additional opportunities for interdisciplinary interactions will be provided by the discussion on central metabolism and the contribution of key metabolic substrates by the microbiota. The latest discoveries will be discussed in the context of basic biology and how it can be exploited to design new therapeutics targeting inflammatory and metabolic disorders.