Governments cannot provide public goods effectively when they lack information about their delivery. Citizens, for their part, experience deficient or absent public services, but they lack incentives to provide monitoring when they do not expect governments to be responsive to their concerns. Over time, this reinforcing cycle creates what we term the valley of disengagement. We investigate how to activate and sustain citizen engagement in governance given the challenges posed by this vicious cycle. In two field experiments in Kampala, Uganda, we recruited citizens to report on solid waste services to the municipal government. We find that neighbors' and leaders' nominations of reporters and public announcements about reporters' activity do not increase citizen monitoring. However, government responsiveness to reporters boosts participation over several months, highlighting the critical role of timely and targeted responsiveness by governments for sustaining citizen engagement.