Enterprise architecture (EA) is a description of an enterprise from an integrated business and IT perspective intended to improve business and IT alignment. EA literature describes many detailed EA methodologies, artifacts and frameworks to organize them. However, establishing EA practice still remains a challenging endeavor with a low success rate. On the other hand, this is not surprising since most organizations successfully practicing EA do not follow EA methodologies and frameworks strictly but adapt them to their own needs or even use them only as idea contributors. Therefore, in order to improve the success rate of EA initiatives, it is necessary to understand better how exactly successful companies adapt EA methodologies in practice. In particular, we argue that the most significant problems in EA practice arise because the usage of individual EA artifacts in practice is poorly understood. In this paper we describe how we are going to investigate the usage of EA artifacts to close this gap.