A critical process in the development and implementation of an expert system is validation of that expert system. There has been substantial research on techniques for validation; however, there has been little analysis of how much validation to do, or how to integrate the multiple agent nature of validation into the validation process. This paper develops a model that employs a probability of fuzzy events model of the process to determine how much validation should be done in a multiple agent setting. An example is given to illustrate the use of the model.