Today’s enterprises are confronted with an ever-changing environment demanding continuous (digital) transformation. Currently enterprise architects tend to guide these changes with so called 'one size fits all' architectural approaches. However, tuning such approaches to a variety of change situations is difficult. There is a call for a more flexible instrument among practitioners that is designed to be tailored to the context of a specific situation. Such fit for purpose enterprise architecture approaches have the potential to play a key role in the current times of digital transformation. In this paper we present the first steps towards a situational enterprise architecture approach that is based on differentiating between subsystems within organizations, by defining which characteristics of subsystems are relevant to determining the correct enterprise architecture approach.