We study the effect of photo ID laws on voting using a difference-in-differences estimation approach around Rhode Island’s implementation of a photo ID law. We employ anonymized administrative data to measure the law’s impact by comparing voting behavior among those with drivers’ licenses versus those without, before versus after the law. Turnout, registration, and voting conditional on registration fell for those without licenses after the law passed. We do not find evidence that people proactively obtained licenses in anticipation of the law, nor do we find that they substituted towards mail ballots which do not require a photo ID.