Politicians shirk when their performance is obscure to constituents. We theorize that when politician performance information is disseminated early in the electoral term, politicians will subsequently improve their performance in anticipation of changes in citizens’ evaluative criteria and possible challenger entry in the next election. However, politicians may only respond in constituencies where opposition has previously mounted. We test these predictions in partnership with a Ugandan civil society organization in a multiyear field experiment conducted in 20 district governments between the 2011 and 2016 elections. While the organization published yearly job duty performance scorecards for all incumbents, it disseminated the scorecards to constituents for randomly selected politicians. These dissemination efforts induced politicians to improve performance across a range of measures, but only in competitive constituencies. Service delivery was unaffected. We conclude that, conditional on electoral pressure, transparency can improve politicians’ performance between elections but not outcomes outside of their control.