Deposition of soot generated from fires is important for tenability, smoke management, detector response, and fire forensics. Previous versions of Fire Dynamics Simulator (FDS) did not account for soot deposition, but FDS 5.3.1 includes an optional soot deposition model based on thermophoresis and turbulent deposition. This thesis analyzes the implementation of these deposition mechanisms independently. Predictions using FDS 5.5.1 are compared with measurements from three existing test series that involve small-scale hood tests, corridors, and large compartments, with heat release rates of 2 kW - 2 MW. Predictions of optical densities for well ventilated compartments generally agreed with experimental data. FDS over predicted optical density for small fires in large compartments and under predicted the mass deposition on surfaces in the small-scale hood test. Compartments without vents indicate that decreased smoke production rates or increased deposition rates would improve the agreement.