An organisational approach to European integration focuses on individual actors’ organisational context in order to account for their behaviour, interests and identities. Intergovernmentalists usually preclude any profound impact of EU institutions and organisations. Institutionalists (other than rational choice institutionalists), on the other hand, claim that EU institutions are able to shape and reshape individual actors’ preferences and sense of belonging. Seen from an organisational perspective, however, institutionalists often fail to specify (and theorise) the organisational components that institutions may contain. This “unpacking” of institutions is necessary in order to clarify the conditions under which transformation of actors and policy processes might occur. The paper tries to illustrate what an organisational approach has to offer in fields like committee governance and Commission decision making. In addition, organisational theory provides a yardstick for assessing the degree of overall system integration.