Particle-surface collisions have broad influence in various processes of interest in science and technology. A simple, conservation-of-energy model has been proposed(1, 2) for characterizing the simplest particle-surface-collision, namely, the idealized collision of a homogeneous, solid, non-rotating particle (such as a sphere) moving at normal incidence towards a flat, smooth surface of a solid body in vacuum. Dahneke,(3) Hays and Wayman,(4) and Wall et al.(5) measured particle-surface collisions approaching this simplest one. We describe an extensive set of measured collision data for 1.27 mu m diameter polystyrene spheres striking a polished, fused-silica surface at normal incidence, in vacuum, over a broad range of particle-approach velocities and use the data to test the model. The goal is to determine the level of agreement between the measured data and the predictions of the model and what information may be obtained by the combination of data and model. We find the model fits the measured data well and the combination provides a number of particle-surface properties including the coefficient of restitution, the increase in attractive potential energy during collision, the impact energy (material stress) at onset of particle deformation, rind possibly other properties.