Technical Abstract: Organic dairies face many challenges, one of which is the high cost of purchased organic grains. Molasses may be a less expensive energy alternative. However, anecdotal results have been mixed for farms that used molasses as the sole energy source. This research project quantified animal performance on an organic dairy farm that fed molasses over two grazing seasons. In 2008, 1.36 kg DM of molasses and 0.45 kg DM of a corn-based grain mix was fed to a mixed-breed dairy herd. In 2009, molasses intake decreased (averaging 1.1 kg DM/cow/d) while corn intake increased (1.0 kg DM/cow/d) in response to low body condition scores (BCS) and milk production. Milk production and milk fat were similar across both years, while milk protein was greater in 2009. Milk urea nitrogen was greater than recommended throughout both grazing seasons. Average BCS was higher in 2009. Using the Cornell Net Carbohydrate and Protein System model, energy was the first limiting factor for milk production. Milk production mirrored model predictions in both years. Income over feed costs was greater in 2008, primarily due to higher milk prices and lower corn feeding. Decreasing molasses and increasing corn meal in 2009 did not result in greater productivity or profitability. However, indicators of animal health and nutritional efficiencies such as BCS and milk protein content were slightly improved in 2009. The cost of molasses in relation to corn meal is an important determinant in making feed ration decisions on a case by case basis.