The need for constant transformation of enterprises is omnipresent. A discipline that has been proposed to support the coordination of enterprise transformation is Enterprise Architecture Management (EAM) which has grown to a mature discipline in academia and practice. However, it can be observed in practice that it still is a challenge to introduce such an architectural coordination approach for supporting enterprise transformation. This may be due to the reason that the institutional context of EAM is only little understood, that is, the interplay between the pressures EAM exerts on the organisation and the response strategies of this organisation. The paper reviews existing work on institutional theory and confirms by means of a case study that the institutional factors of cause, constituents, content, control, and context are not only relevant for EAM but may be consistently linked to response strategies of acquiesce, compromise, avoid, defy, and manipulate. Moreover the case study implies to add additional institutional factors for EAM, namely trust and participation.