In this article I analyse whether differences in formal committee structures affect how parliamentary actors organise their work within them. I compare the allocation of members to specialised committees in the Dutch House of Representatives (Tweede Kamer) and the Belgian Chamber of Representatives (Kamer van Volksvertegenwoordigers/Chambre des Représentants) to test whether committee assignments are given more serious consideration when committees are strong. Despite many similarities, both parliaments differ in their internal institutional arrangements: committees in the Chamber of Representatives are, at least formally, considerably more powerful than those in the Dutch Lower House. The article uses the congressional theories of legislative organisation as heuristic devices to deduce several rationales of the assignment process. The role of parliamentary party groups is highlighted. The results indicate the presence of stable, reoccurring patterns in both parliaments. Even in the House of Representatives, where committees present lower opportunity structures, assignments are given due consideration.