One of the fundamental concepts of toxicology is that chemicals act at selective receptors and that such interactions result in phar­ macologic responses which, depending on dose, mayor may not result in toxicity. For us to understand how insecticides produce their toxic effects, we must first understand their molecular interactions with their target receptors. With this in mind, we organized a symposium which was given in conjunction with the XVII International Congress of Entomology in Hamburg on August 21, 1984. The goal of this symposium was to bring together researchers with a wide range of expertise who shared a common interest in the action of insecticides on the insect nervous system. It was decided to restrict the scope of the symposium so that selected topics could be discussed in greater depth. The volume which resulted from this symposium, -Membranes Receptors and Enzymes as Targets of Insecticidal Action-, details a number of bio­ chemical modes of action of insecticides on the insect nervous system. The volume is divided into two sections; the first dealing with the action of insecticides on the GABA-ch1oride channel complex. This section evolves from a discussion of the symptoms of cyclodiene toxicity presented by Dr. D. E. Woolley, to the structure-activity relationships and pharmacology of the channel complex and is concluded with the extremely interesting work of Dr. C. C. Wang on the action(s) of avermectin at this receptor.