This paper investigates the effect of open government provisions on public corruption in the United States. Specifically, it assesses the impact of switching from a weak to a strong state-level FOIA law on corruption convictions for state and local government officials. The evidence suggests that strengthening FOIA laws has two offsetting effects: reducing corruption levels and increasing the probability that corrupt acts are detected. Corruption conviction rates approximately double after the switch, which suggests an increase in detection probabilities. However, corruption conviction rates gradually decline from this new elevated level as the time since the switch from weak to strong FOIA increases. This decline is consistent with officials reducing the rate at which they commit corrupt acts by over fifty percent, and it is still apparent as long as 10 to 15 years after the change in FOIA laws. There is no concomitant change in the corruption convictions of federal officials in these same states.