The physiological and pharmacological roles of pre- and postsynaptic dopamine receptors in modification of neuronal transmission centrally and peripherally will be subjects for intense research during the next decade. As enumerated by Langer, dopamine-sensitive receptors have been described that may inhibit or facilitate release of neurotransmitter substances. It is likely that dopaminergic agents that are highly selective for specific transmitters will be discovered. Likewise, dopaminergic agents that are nonselective (i.e., that modify the function of two or more neurotransmitters) may offer many opportunities for modification of behavior.