Editor's Note. This is the second article in our Perspective on Psychological Measurement Series. In this article J. P. Guilford, who was first exposed to the problems and methods of psychological measurement in the early 1920s, provides a unique perspective on his distinguished career ranging across his varied and very important contributions to the science of psychology and to the methodology of psychological measurement. Based upon experiences with most kinds of methods of psychological measurement, this article presents comments on a variety of uses, including psychophysics, scaling, testing, and factor analysis. Some difficulties are pointed out, some faults are mentioned, and a variety of applications are discussed, some of them unusual.