This book is in a sense an outcome of work I started in 1939, when, as a graduate student at the University of Minnesota, I became aware of L.L. Thurstone's research on what he called “primary mental abilities” and undertook, in my doctoral dissertation, to apply his factor-analytic techniques to the study of abilities in the domain of language. Over the years of my career as a specialist in psychometrics, educational psychology, and the psychology of language I tried to keep abreast of both methodological and substantive developments in factor analysis, and from time to time I found it useful to conduct factor-analytic studies on topics of particular interest to me. Increasingly, however, I sensed the field's need for a thoroughgoing survey and critique of the voluminous results in the factor-analytic literature on cognitive abilities. It was not until 1974, when I came to the University of North Carolina at Chapel Hill as director of the L.L. Thurstone Psychometric Laboratory, that I felt that an appropriate use of my time would be to plan and execute such a survey.

A sabbatical year in 1979–80 supported by the Kenan Fund at the University of North Carolina and by the James McKeen Cattell Fund enabled me to start compiling materials systematically and make visits to prominent investigators in the U.S. and Europe. The major efforts starting in 1983, after I retired from the university, were supported chiefly by grant BNS-82-12486 from the National Science Foundation.