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Anaerobic digestion of dairy manure has the benefits of reducing greenhouse gas emissions, odors, and waste strength while producing biomethane (CH4). This study presents the first year performance data of an on-farm anaerobic digester (AD) on 1200 milking herd dairy farm in Virginia. The AD was designed as a two- stage reactor system operated at mesophilic conditions (38C) with a volumetric manure flow rate of approximately 125 m3/d. The AD performance was evaluated with respect waste stabilization and biogas production. Samples of the digester influent, effluent, and separated liquid were collected at least once a month and analyzed for manure characteristics including pH, solids, chemical oxygen demand (COD), volatile fatty acids, and nutrient content. Biogas quantity and quality were also routinely monitored. Average concentrations of total and soluble COD decreased by 32 and 55%, respectively, between the digester influent and effluent. Average total volatile fatty acid concentrations were reduced by 91.2%. The total and volatile solids reductions were 30 and 35%, respectively. Average daily biogas production was 5,636 m3 (standard cubic meters) with an average methane concentration of 54%. Biogas was converted to electricity by an on-farm generator which on average produced 360 KWH of electricity per day. The electricity produced was fed to the local grid. Excess biogas was flared or used in a boiler when engine is not running.