The circadian clock orchestrates the coordinated rhythmicity of numerous metabolic pathways to anticipate daily and seasonal changes in energy demand. This vital physiol. function is controlled by a set of individual clock components that are present in each cell of the body, and regulate each other as well as clock output genes. A key factor is the nuclear receptor, Rev-erbα, a transcriptional repressor which functions not only as a clock component but also as a modulator of metabolic programming in an array of tissues. This review explores the role of Rev-erbα in mediating this crosstalk between circadian rhythm and tissue-specific biol. networks and its relevance to organismal physiology.