Corruption is the great disease of government. It undermines the efficiency of the public sector in many countries around the world. We experimentally study civic engagement (CE) as a constraint on corruption when incentives are stacked against providing CE. We show that CE is powerful in curbing corruption when citizens can encourage each other to provide CE through social approval. Social approval induces strategic complementarity among conditional cooperators which counteracts the strategic substitutability (which tends to limit beneficial effects of CE) built into our design. We also show that civic engagement in the lab is correlated with civic engagement in the field, and that the effects of social approval are surprisingly robust to framing in our setting.