In this paper we outline a new methodical approach for integrating theories into the design research process. Incorporating theories in design projects allows design researchers to reason on the effects of the IT artifact prior to its realization. We argue that design decisions should be transparent claims of utility based on theory-grounded arguments. Documenting design decisions requires the design researcher to integrate appropriate theories and document the rationale behind a particular design decision. Overall, we demonstrate on the example of constructing a new modeling grammar how to integrate theories in the design research process and discuss conflicts which occur when applying these theories.