This is the third Proceedings book to arise from biennial conferen- ces on the Trace Amines. Since our first meeting in 1983 in Edmonton, Canada, progress has been brisk and, as will be seen from the ensuing pages, it is now possible to include major contributions from inverte- brate neurobiologists as well as receptorologists. In the opening ses- sion we heard about the distribution of the trace amines-now clear- ly a misnomer-in insects and the pharmacological, receptor, and syn- aptic characteristics of octopamine and tryptamine as well as the pos- sibility of monoamines in general being targets for insecticide discov- ery. In mammalian brain the distribution and characterization of the tryptamine receptor has proceeded to the point where two types have been described as well as novel agonists and antagonists, and, for the first time, a binding site for p-tyramine has been described. The com- bination of lesions and pharmacological and metabolic manipulations now permits the mapping of trace aminergic pathways, and the rap- idly accumulating evidence from releasing drugs, in situ microdialy- sis, iontophoresis, and second messenger systems lends credence to the claim that the trace amines possess neuromodulatory functions.