Technical Abstract: Conservation and nutrient management planners need an assessment tool to accurately predict phosphorus (P) loss from agricultural lands. Available tools are either qualitative indices with limited capability to quantify offsite water quality impacts or prohibitively complex quantitative process-based models. Pasture Phosphorus Management (PPM) Plus was developed as a user-friendly P loss prediction tool based on the Soil and Water Assessment Tool (SWAT), a popular comprehensive hydrologic and water quality model. It is simple enough for use by farmers and conservation planners, applicable for both cultivated fields and pastures, and predicts P loss using a wide variety of management options and conservation practices. SWAT hydrologic components were calibrated, and databases were developed to allow application anywhere in the State of Oklahoma. PPM Plus uses a modified SWAT model that includes a number of soil P algorithm updates and improved representation of several conservation practices. This tool was successfully validated using 283 field years of measured data by White (2007). PPM Plus allows the generation of more effective conservation plans by allowing planners to evaluate P and sediment losses resulting from a particular management strategy prior to implementation.