Bridging the literature on gender and politics, democratization, and political parties, this article investigates the causes of parties’ varying compliance with electoral quotas. Whereas research has so far focused on parties’ willingness to comply, this article sheds light on their ability to do so. It suggests that the more quotas parties have to comply with, and the more complex the quotas’ designs, the more difficult implementation becomes for the organizationally weak parties that we often encounter in new democracies. The argument is developed and substantiated in a comparative analysis of parties’ quota compliance in the 2018 Tunisian local elections. Although the Islamist party was able to comply fully with all quotas (for women, youth and people with disabilities), small secular parties lost a number of lists and state funding due to non-compliance. While the quotas were highly effective in securing group representation, they had repercussions on party and party system consolidation.