By the early 1970s the psychology of age had become an extremely important topic in the field. In the present book, originally published in 1973, the authors are particularly concerned with the subject of intellectual functioning. The assessment of intellect in the aged has many important theoretical and practical implications. At the same time, this work was of vital importance to the problems of medical illness in the aged, particularly with psychiatric and neurological diagnosis. Intellectual functioning is severely affected by psychiatric illness – but the intellectual difficulties associated with functional disorder in the aged may be quite different from those in the young. The cross-fertilization of psychiatric and psychological work on problems of the aged at the time left much to be desired. It was the hope of the present book to contribute towards a much firmer amalgamation of the two attitudes.