A sponsored effort was made to develop an automated system for determining the impact characteristics of soils and playing surfaces in situ. Most of the earlier measurements of this type yielded only information on peak deceleration. The equipment developed under this project consists of a portable measurement unit employed for data acquisition and a personal computer programmed for analysis of data from individual tests and for statistical analysis across an ensemble of tests. The data acquisition subsystem is comprised of an instrumented mass that is dropped from a fixed height through a guide tube and a battery-powered vibration analyzer that can capture the deceleration curve in memory for display or later recovery. The data set from each individual drop or averaged set of drops is downloaded to the computer and written to a Winchester drive. The analysis program uses a measured impact velocity and calculates maximum deceleration level, total duration of impact, several rates of change, and surface deformation. Recent additions to the program also provide determinations of severity index, rebound velocity, and rebound ratio when appropriate. The deceleration curve and all calculated parameter values are displayed on the system monitor; a hard copy of the display can be produced on a dot-matrix printer. A separate algorithm supports analysis of a set of data files selected by the operator; all selected files are combined into a single file on which statistical operations can be performed. Possible uses for the system include testing playing surfaces for injury potential and regular diagnostic testing of surfaces which must be maintained in a specific condition. The system uses widely available processing equipment and only the drop unit itself is custom made.