In general, antipsychotic agents have diverse actions on a wide range of neurotransmitter systems. Data strongly suggest that a number of these systems may play a role in the regulation of body weight. In addition to having very distinct pharmacologic profiles, individual agents possess discrete weight gain liabilities. This article briefly reviews the evidence for the involvement of specific neurotransmitter systems in the control of body weight and describes the relevant pharmacologic characteristics of individual antipsychotic agents. By comparing the pharmacologic profiles of specific antipsychotic agents with their respective weight gain liabilities, this article attempts to gain an insight into the specific receptors underlying a drug's propensity to induce weight gain. However, there is still much to be learned concerning weight control mechanisms, and the role of many of the receptors at which antipsychotic agents are active remains unclear. In spite of this, an overview of current knowledge in the field may facilitate prediction of a potential novel antipsychotic agent's weight gain liability.