Abstract: Slope stability analysis for regions has traditionally been completed using qualitative methods. This study develops models for determining quantitative factors of safety for any trial slope within a region. The models are based on geologic and engineering analysis of factors contributing to failure within the San Clemente, CA region. A data base of quantifiable variables was developed from geotechnical reports and field measurements to complete subsurface slip plane models and calculate slope by slope factors of safety using the simplified Janbu equation. Results for model calculations compare favorably with detailed slope analysis factors of safety determined by geotechnical engineers. The study method of regional analysis provides more detailed information on the balance of key forces acting upon hillsides than traditional approaches. It is adaptable to other regions and may be adaptable to GIS applications.