A survey was conducted in Spain in 1986 to estimate the number of people with disabilities and to identify the impairments which had given rise to them. The survey also set out to identify the causes of these impairments and to analyse the nature and extent of the handicaps resulting from these impairments and disabilities. The frame of reference for the survey was the WHO International Classification of Impairments, Disabilities, and Handicaps (ICIDH), which was adapted in a number of ways. The most radical departure was to begin the survey with disabilities, which were considered easier to identify. 15% of the population presented a disability, the rate mostly increasing with age, with substantial differences between the sexes and pronounced gradients in relation to socioeconomic status in some cases. Analysis of disabilities and impairments by administrative area also revealed some significant geographical variations. The study of handicaps posed some particularly complex problems of methodology. In conclusion, the work of the Spanish survey was facilitated by the use of the ICIDH, but this classification requires several substantial modifications before it can be systematically used in surveys of this type.