The impact of cash transfer programs on the accumulation of human capital is a topic of great policy importance. An attendant question is whether program effects are larger when transfers are "conditioned" on certain behaviors, such as a requirement that households enroll their children in school. This paper uses a randomized study design to analyze the impact of the Bono de Desarrollo Humano (BDH), a cash transfer program, on enrollment and child work among poor children in Ecuador. There are two main results. First, the BDH program had a large, positive impact on school enrollment, about 10 percentage points, and a large, negative impact on child work, about 17 percentage points. Second, the fact that some households believed that there was a school enrollment requirement attached to the transfers, even though such a requirement was never enforced or monitored in Ecuador, helps explain the magnitude of program effects.