While an extensive (US) literature stresses the importance of procedural rules in the evolution of parliaments as well as in the legislative process, very few studies have focused on the European Parliament (EP) rules. Whereas the EP's empowerment was significantly influenced by its rules of procedure, the reforms of these rules and their consequences for political actors remain understudied. This paper aims to contribute to the theorisation of the EP's institutional dynamics in light of the North American theories. It examines the challenges faced by the EP due to the rationalisation of its deliberation and the consequences of the procedural changes for the institution, its members and its public image. On the basis of a qualitative analysis of the revisions of the EP rules of procedure from April 1979 to January 2017, it is shown that institutional efficiency has become an objective in itself, but the reforms have had a strong distributive effect by reducing members of the European Parliament’s freedom of action. The various reforms have strengthened ‘democracy through parliament’ at the expense of ‘democracy in parliament’, which could have tremendous consequences for the EP's image among public opinion.