This report introduces a Lagrangian-based Particle Tracking Model (PTM) developed by the Coastal Inlets Research Program (CIRP) and the Dredging Operations and Environmental Research Program (DOER) being conducted at the U.S. Army Engineer Research and Development Center. The PTM's Lagrangian framework is one in which the sediment being modeled is discretized into a finite number of particles that are followed as they are transported by the flow. Lagrangian modeling is insightful for modeling transport from specified sources. Many particles are modeled such that transport patterns are representative of all particle movement from the sources. The model operates in the Surface-water Modeling System (SMS) interface and allows the user to simulate particle transport processes to determine particle fate and pathways. Waves and currents used in the PTM as forcing functions are developed through other models and input directly to the PTM. PTM Version 1.0 input files are from the ADCIRC or M2-D depth-averaged hydrodynamic models and STWAVE and WABED wave models. Other models can be used as input by first converting their output to ADCIRC, M2- D, or STWAVE and WABED formats. The general features, formulation, and capabilities of PTM Version 1.0 are described in this report, including the basic components of the model, model input and output, and application guidelines. Other chapters of this report provide detailed information about the PTM s theory, numerical implementation, and examples that demonstrate the model s potential usage in practical applications. Sediment pathways are readily identified within the Lagrangian modeling framework of the PTM for conditions with sharp gradients in suspended solids (plumes, for example), where numerical diffusion in Eulerian models would require very small grid spacing to provide reliable solutions.