The expulsion of party members for the expression of dissent is a common practice in democratic states around the world, which can have momentous consequences for individual parties and the political system at large. In this article, we address the question of whether limitations on party members’ free speech can be defended on normative grounds. Drawing on a conception of parties that sees them as broader membership organisations that allow citizens to exercise political agency in a unique fashion, as well as on insights from the broader normative-theoretical literature on organisations, we build a strong presumptive case that interference with party members’ political freedoms is normatively problematic. Exploring numerous weighty arguments in favour of limiting freedom of speech within parties, we find that none of them provides a knock-down argument against our case. The argument we advance has important implications for contemporary theoretical debates about parties and partisanship, and for the regulation of parties’ internal affairs more generally.