The British Ability Scales (BAS), published in 1979 (after a national standardization on a representative sample of British children), were revised and republished in January 1983. The BAS is an individually administered cognitive test battery for children aged between 3 and 17 years. It has considerable breadth of test content and provides a greater degree of flexibility in use and a wider range of measurement facilities than in any previously published test battery. The major aim of the BAS is to provide diagnostic information on cognitive strengths and weaknesses, although it is possible, in addition, to calculate intelligence quotients. Innovations in content include scales based on theories of child development and cognitive theory. It has a number of technical innovations such as the use of Rasch scaling and expectancy tables. The BAS is not based restrictively on any single model or theory of intelligence or abilities, but is linked to the work of Piaget, Kohlberg, and Olver and Hornsby. Although a considerable amount of statistical information is provided in the technical handbook, the 23 scales have been primarily designed as a useful assessment test battery for the practitioner. (Author/PN)