Studies of candidate selection have shown that formal rules alone cannot explain the low number of female candidates. Scholarship focusing on both demand and supply sides of political recruitment, and those attentive to the interplay between formal and informal rules, provide fuller explanations. This article shows how informal and formal rules interact in accommodating and competitive ways to produce differing gendered effects within nine Dutch political parties. Formal rules were mapped by content analysis, and informal rules from 23 semi-structured elite interviews. The findings show that the institutional rules and norms which positively increase the selection of male candidates are: being an active party member; having political experience; the incumbency bonus. This study contributes to established literature(s) on the underrepresentation of women by studying candidate selection across parties, with specific emphasis upon the interplay between formal and informal rules and their gendered effects, through the lens of feminist institutionalism.