The development of access to documents and open meetings provisions by the Council of Ministers of the European Union shows an interesting pattern: before 1992 no formal transparency provisions existed, between 1992 and 2006 formal transparency provisions dramatically increased and since 2006 this increase has come to a halt. This paper aims to enhance our understanding of these shifts by conducting a historical institutional analysis of policy change. As explanatory factors, we consider the preferences and power resources of member states, as well as external catalysts and social structures. We conclude that the current revision deadlock is more stable than the situation before 1992, because now the pro-transparency coalition and transparency-sceptic Council majority have entrenched their positions. Nevertheless, and in spite of Council entrenchment, we expect that Council transparency will continue to develop in the longer term, under the pressure of increasingly influential outside actors, particularly the EP.