The history of the concept of psychological androgyny is very much the history of research on its components, masculinity (M) and femininity (F). Two very different approaches to MF measurement are discernible in the literature: the sex difference approach aims to distinguish men from women reliably, while the sex stereotype approach is concerned with comparing individuals' self-concepts to widely-held beliefs and expectations about men and women, regardless of how valid these stereotypes are. Data from 160 men and women are considered in a study designed to overcome the methodological problems of sex stereotype MF scales now in use, and to investigate the relationship of sex stereotypes to sex differences and male-female relations. Sex stereotypes are found to markedly exaggerate and misrepresent self-rated sex differences. Procedures for examining the correspondence between self-ratings and the way one is perceived socially are suggested as a means of testing the utility of paper-and-pencil approaches to MF measurement. Speech cues (verbal and non-verbal) are among the most important bases for social perception, and are nominated as deserving of further attention in this context. (Author)