Abstract Transparency is an important principle in all democratic polities. This chapter begins by considering the different values served by transparency. The focus then shifts to the status of transparency in the pre-Lisbon world and the way in which the concept was accorded greater prominence in the last decade of the previous millennium. This is followed by consideration of the various ways in which transparency is protected in the Lisbon Treaty. The analysis then turns to an examination of an important facet of transparency concerned with access to documents.