This book constitutes the proceedings of a NATO Advanced Research Workshop held in El Escorial (Spain) from 22 -27 May 1988 with the title Processing of sensory information in the superficial dorsal hom of the spinal cord. Included in the book are reports of most of the main lectures given at the meeting, section introductions written by each session Chairman, section reports compiled by session rapporteurs and some short papers invited from authors of communications given in poster form. The latter were selected on the basis of being immediately relevant to the topic of the workshop and of originating from a laboratory not represented by the main speakers. All in all we believe that the reader can get a fair idea of the structure and general character of this Workshop. The overall aim of the meeting was to review the current state of knowledge on the role of the superficial dorsal horn of the mammalian spinal cord as a nucleus of relay and modulation of the somatic and visceral sensory input to the central nervous system. In this context, the contribution of this spinal cord region to the appreciation of pain was a central topic of discussion. Over the last decade there has been a considerable increase in anatomical, physiological and neurochemical studies of the superficial dorsal horn.