In the near-surface environment, ground penetrating radar (GPR) sections can be difficult to interpret, even with the use of advanced processing techniques. With the application of three-dimensional, finite-difference time-domain modeling, we are able to simulate GPR wave propagation and evaluate the nature of the recorded signals. Mathematical models of the propagating electromagnetic wave are generated using a staggered, fourth-order O(2,4) finite difference scheme utilizing orthogonal, cartesian grids. Realistic antenna configurations and source signal forms are developed with practical dielectric models determining the subsurface material properties. These models are based on the superposition of single relaxation mechanisms allowing frequency-dependent, conductive, inhomogeneous, anisotropic materials to be incorporated into the scheme. To assess model performance, a series of 900 Mhz radar sections were collected over a purpose built test facility having quantifiable features and known material properties. Separate models generated from both known and estimated properties were compared to the observed data and in general, correlate well. These models provide important information on the nature of the subsurface and assist in the application of advanced processing and interpretational methods.