The Susceptibility Model Assessment and Range Test (SMART) Project is a joint-service initiative tasked to define a model credibility assessment methodology that will assist DoD decisionmakers with model accreditation decisions. This methodology will integrate the key features of verification, validation, and configuration management and, as the project name implies, will base most of the validation efforts on comparisons with range test data. The various elements of the SMART methodology will be demonstrated by an actual application to a set of five susceptibility models selected by a joint-service prioritization. This report describes a two-phased approach for the SMART model validation component of the overall methodology and is based on an analogy between model validation and weapon system test and evaluation. It incorporates the functional element decomposition and validation previously developed for the SMART project as Phase I and adds an integrated model validation as Phase II. Neither Phase I nor Phase II alone is sufficient for model validation, but together they provide a complementary and powerful methodology.