The Colorado Rockfall Simulation Program (CRSP) was developed to model rockfall behavior and provide a statistical analysis of probable rockfall events at any given site. Version 4.0 is used for Windows 95, 98, and NT systems. Includes: introduction, previous work and background, methods, results, discussion of results, conclusions, recommendations, use of the CRSP program, references, appendix. 61 figures. 8 tables. Downloadable program.