Two key processes in sentence processing are syntactic movement and the computation of agreement. We report two studies exploring the consequences of gender mismatch in the comprehension and production of French object relatives, requiring both the computation of movement and agreement. We show that gender mismatch enhances comprehension while penalizing production. We argue that comprehension and production are sensitive to different kinds of intervention: while comprehension is sensitive to similarity-based interferences, which are reduced by feature mismatch, production is sensitive to attraction effects, which arise in configurations of feature mismatch.