First, performance and cost measures were determined for individual elements of a perimeter (e.g., walls, cameras). Next, a mathematical formulation was developed to assess the cost effectiveness of perimeter cross-sections as a whole. The mathematical model provided the basis for a computer model. The computer model uses the cost and effectiveness measures of barriers, alarms, and response forces to compose a picture of the cost-effectiveness of any perimeter cross-section configuration. For any perimeter cross-section, the model produces a number of main results. The equivalent annual cost of the perimeter is calculated using discounted cash flow techniques, taking into account the installation and maintenance cost of the chosen systems. The calculation of an overall detection probability and intervention probability is based on a conceptual model of the perimeter cross section. At the core of the model is a table of probabilities relating the likelihood of success of various attack styles under a variety of weather conditions. The model has been used to study establishments as the first stage in the planning process for defining a prison's perimeter. 2 figures and 1 reference. (Author abstract modified)