Multiple group factor analysis is described and illustrated through a simulation involving 5,000 examinees. The estimation process of the group factors were implemented using the TESTFACT program of Wilson and others (1987). Group factor analysis is described as a special case of confirmatory factor analysis. Group factors can be computed based on the collapsed gradient and Hessian matrix by summing up the elements according to the item group structure. This full information method can control guessing and the difficulty of each item. Implications of the simulation for additions to the TESTFACT program are discussed. Confirmatory factor analyses, including the group level factor structure, are considered appropriate processes for analyzing test data. Nine tables present data from the simulation study. (SLD)