The Vanderbilt Mouse Metabolic Phenotyping Center (VMMPC) was founded in 2001 to advance medical and biological research by providing the scientific community with standardized, high quality phenotyping services for mouse models of diabetes, diabetic complications, and obesity. The VMMPC consists of five cores. The Administrative Core provides scientific, financial, and administrative leadership. This Core also oversees service requests, data management, and tracks mice studied at the VMMPC. The Administrative Core is also responsible for the VMMPC outreach and educational program. The Animal Health and Welfare Core evaluates mice submitted to the VMMPC, oversees the health and welfare of the colony, and ensures compliance with regulatory bodies and MMPC guidelines. Services provided by the Metabolic Regulation Core (MRC) emphasize methodology to study insulin action, hormone secretion, and metabolism in the conscious, unstressed mouse. The MRC also has a sophisticated capacity to assess organ or islet function in isolation and can apply state-of-the-art imaging techniques. The Body Weight Regulation Core has a range of tests to study determinants of energy balance. These include energy expenditure, feeding behavior, physical activity, body composition, mitochondrial function, and bariatric surgery procedures. The Analytical Resources Core (ARC) receives samples generated from VMMPC testing and from experiments conducted outside the VMMPC. Analyses performed by the ARC are specific to the mouse and are scaled to accommodate small sample volumes. ARC services range from assessment of hormones, analytes, lipids, lipoproteins, and atherosclerotic lesions to innovative metabolic flux analysis. The VMMPC exists because of the insight of leadership at the NIDDK, a generous commitment of space and resources from Vanderbilt University School of Medicine, and a well-conceived infrastructure. But the main reason the VMMPC works as well as it does is because of the people that comprise it. The VMMPC exists because of a faculty that is willing to make technology and guidance available to the scientific community and a staff that is so skilled and committed that scientists are willing to entrust their mice and valuable samples with them.