Over the past few years there have been considerable advances in our understanding of the normal development of vision and in our ability to detect and meaSl1re visual impairment in early childhood. It was appropriate, therefore, that a workshop, sponsored by the European Communities, should be held on the 'Detection and Measurement of Visual Impairment in Pre-verbal Children.' This workshop, which was held at the Institute of Ophthalmology, London, between 1 and 3 April 1985, brought together visual physiologists and ophthalmologists who exchanged and discussed ideas of mutual interest. After an introductory session when the normal development of vision and the causes of visual impairment were reviewed, there were sessions devoted to the theoretical aspects of electrophysiological and psychophysical tests, the measurement of visual acuity in pre-verbal children, the measurement of other visual functions, and visual screening of pre-verbal children. This volume contains the papers presented at the workshop, and transcripts of the various discl1ssions that took place. It was a measure of the success of the workshop that participants from several different disciplines were able to have fruitful discussions and to suggest areas of common interest where collaborative ventures could usefully be pursued. It is hoped that this venture will be followed by others where a mul ti­ disciplinary approach will improve both our knowledge of visual handicap in childhood and our management of this important group of sensorily impaired children.