The energy requirements of the brain are very high, and tight regulatory mechanisms operate to ensure adequate spatial and temporal delivery of energy substrates in register with neuronal activity. Astrocytes—a type of glial cell—have emerged as active players in brain energy delivery, production, utilization, and storage. Our understanding of neuroenergetics is rapidly evolving from a "neurocentric" view to a more integrated picture involving an intense cooperativity between astrocytes and neurons. This review focuses on the cellular aspects of brain energy metabolism, with a particular emphasis on the metabolic interactions between neurons and astrocytes.