Agricultural operations, including horse farms, can contribute non-point source (NPS) pollution to surface water. The use of best management practices (BMPs) is one of the most effective ways to prevent damage to surface water from NPS pollution. In Maryland, mailed survey studies have assessed the use of BMPs, however a visual assessment of horse farms is necessary to validate survey results. An observational field study was conducted to assess BMP use, soil and pasture quality, and to create a model to predict soil erosion on Maryland horse farms. Fifty-one farms were selected based on stocking density, farm use, and presence of water on property. In each pasture with grazing horses the correct use of BMPs was assessed, grass height and vegetative cover were measured, and composite soil samples were collected. Less than half of the 18 assessed BMPs were being used by participants. Although most participants maintained the recommended vegetative cover and grass height, soil erosion was a major problem in pastures. The majority of farms had optimum soil nutrient concentrations (Ca, K, and P), excessive Mg values, and basic soil pH. Vegetative cover and grass height measurements were positively correlated to stocking density (P < 0.0001 and P = 0.0004, respectively). Farm use was the only variable that predicted soil erosion on farms (P = 0.006). Farms used for pleasure were least likely to have soil erosion whereas farms used for breeding were more likely to have soil erosion (P = 0.0058). Despite the low to moderate adoption of BMPs, the maintenance of recommended vegetative cover and grass height as well as optimum values of soil nutrients indicate participating Maryland horse farms have a low potential for nutrient losses to surface waters.