Agenda setting determines whether and how topics are discussed and voted in parliament. Many parliaments delegate this task to a specific body charged with coordinating parliamentary business. However, we know little about the composition and powers of these “coordination committees” (CC). This paper maps the existence, composition, and institutional powers of coordination committees across 31 European parliaments. It shows that CCs exist in most parliaments and have a relatively similar composition, usually including the president of parliament, their deputies, and party group representatives, but vary strongly in their agenda-setting powers. Exploring whether this variation is related to the functional need for coordination, we find limited evidence that larger sizes of parliaments and higher ideological polarization between parties are associated with stronger coordination committees. In terms of this HSR Special Issue, we show that CCs as horizontal collective actors exist even in a hierarchical organization such as a parliament and have relevant, albeit variable, resources.