The offsite drift of pesticide from spray operations is an ongoing source of concern. The SPRAY TRANsport (SPRAYTRAN) system, documented in this report, incorporates the near-field spray application model, AGDISP, into a meso-scale atmospheric transport model. The AGDISP model is a near-field modeling technology used to evaluate primary drift from a single pesticide application to a single row crop field during neutral atmospheric conditions over level terrain with uniform surface characteristics under the assumption of uniform and constant meteorology. The SPRAYTRAN system incorporates the on-field deposition and near-field spray drift results from AGDISP into a meso-scale transport model through a geographic information system-based user interface. SPRAYTRAN also extends and uses the DUST TRANsport (DUSTRAN) modeling system to enhance the assessment of offsite drift of pesticides. DUSTRAN is being developed for the U.S. Department of Defense to assess training/testing range dust-oriented pollutant contributions to local and regional air quality, to help manage dust-generating activities, and to help develop dust-mitigation strategies. SPRAYTRAN allows the assessment of potential pesticide exposures from multiple applications to multiple fields in variable terrain with time-varying, non-uniform meteorology.