Trust is the willingness to make oneself vulnerable to another person's actions, based on beliefs about that person's trustworthiness. This article focuses on interpersonal trust and trustworthiness between two people, a trustor and a trustee, as measured in laboratory experiments. A trustee behaves trustworthily if he voluntarily refrains from taking advantage of the trustor's vulnerability. Trust applies to all transactions where the outcome is partly under the control of another person and not fully contractible. The article discusses measurement issues, the motives for and influences on trust and trustworthiness (incentives, repetition and demographic variables) and questions of external validity.