Since joining the Open Government Partnership in 2011, the Indonesian Government has shown some commitment towards implementing initiatives that increase citizen voice and social accountability. These include a series of ICT-based complaint-handling systems that give members of the public an opportunity to highlight problems with the delivery of public services to those in a position to fix them. Yet the reach and uptake of these systems – which are both national and local – varies considerably across the country, for a number of reasons. This research examines four cases of complaint-handling systems. It asks how, and by whom, complaint-handling systems are used, in order to establish what makes a complaint-handling system succeed or fail.