This paper investigates the paradox in post-conflict societies of continued marginality of cross-ethnic parties despite significant convergence in public attitudes and identities. In so doing, it examines the argument that parties that attempt to reach across the divide are constrained by consocational institutions designed to accommodate rival identities in such environments. The paper explores this puzzle in the context of Northern Ireland, drawing upon qualitative evidence from elite interviews and focus groups collected in 2012 and 2013. It concludes that cross-community parties operating in the region do encounter formal institutional barriers, but that such barriers only partially explain the phenomenon and an interplay between formal and informal constraints underlies their position of relatively limited electoral success.