We examine the incentives to self-select into politics and how they depend on the transparency of the entry process. To this end, we set up a two-stage political competition model and test its key mechanisms in the lab. At the entry stage, potential candidates compete in a contest to become their party's nominee. At the election stage, the nominated candidates campaign by making non-binding promises to voters. Confirming the model's key predictions, we find in the experiment that dishonest people over-proportionally self-select into the political race; and that this adverse selection effect can be prevented if the entry stage is made transparent to voters.