Deterministic Level I Stability Analysis (DLISA) and probabilistic Level I Stability Analysis (LISA) models provide information for a slope stability analysis. These computer codes have been developed, tested, and validated by U. S. Department of Agriculture Forest Service researchers. The purpose of this research was to provide engineers and scientists a personal computer program for evaluating potential slope instability within planning areas in forested uplands. Physical soil values within the infinite slope equation are evaluated within DLISA for possible frequency distributions. LISA, the probabilistic computer program, adds a stochastic simulation by the Monte Carlo method of these frequency distributions. The result from these analyses is a probability of slope failure. Potential shallow landslides, such as debris flows, have been evaluated since 1987 and can be predicted with DLISA and LISA.