Parties neither cease to exist nor cease to compete for office when the general election is over. Instead, a new round of competition begins, with legislators as voters and party leaders as candidates. The offices at stake are what we call “mega‐seats.” We consider the selection of three different types of mega‐seats—cabinet portfolios, seats on directing boards, and permanent committee chairs—in 57 democratic assemblies. If winning parties select the rules by which mega‐seats are chosen and those rules affect which parties can attain mega‐seats (one important payoff of “winning”), then parties and rules should coevolve in the long run. We find two main patterns relating to legislative party systems and a country's length of experience with democratic governance.