When people choose what messages to send to others, they often consider how others will interpret the messages. In many environments, particularly in politics, message receivers engage in motivated reasoning, distorting how they process information in directions they find more attractive. This paper uses two online experiments to study what information senders choose to send to receivers on topics that evoke politically-motivated beliefs. Experiment 1, conducted using a sample of social media users, studies the effect of incentivizing senders to be perceived as truthful. These incentives cause senders to send less truthful messages. With these incentives, senders send more false information when it aligns with receivers' motivated beliefs, even controlling for receivers' current beliefs. Receivers do not anticipate the adverse effects of senders' incentives. Experiment 2 isolates the role that motivated reasoning plays by constructing an environment in which receivers assess the truthfulness of messages from a computer and senders choose which message to be paid for. Senders predict that politically-motivated reasoning impacts receivers' inference, they demand information about receivers' political preferences, and they use the receivers' politics to strategically choose less truthful messages.