The composite direct product (CDP) model is a multiplicative model for multitrait-multimethod (MTMM) designs. It is extended to incomplete MTMM correlation matrices where some trait-method combinations are not available. Rules for omitting trait-method combinations without resulting in an indeterminate model are also suggested. Maximum likelihood estimation and the log absolute correlation procedure are used to fit the model, and are found to yield similar results. The balanced incomplete MTMM design tends to yield more accurate estimates than the randomly missing design.