Neurotransmitter transporters have long been known to recognize related compounds as substrates, resulting in the accumulation and release of so-called "false transmitters." In this issue of Neuron, Zhou et al. show that when serotonin levels are elevated by inhibition of either serotonin reuptake or of monoamine oxidase, dopamine neurons accumulate serotonin. The results suggest that release of serotonin by dopamine neurons may contribute to the effects of multiple major classes of antidepressants.