At this point it may be well to give a few words of warning in regard to possible misuses of the M-F test.SEX AND PERSONALITY be as accurate as possible, both forms of the test should be administered and the average taken of the two scores. Types of investigation in which the test should be helpful include, among others, the relationship of masculinity and femininity of temperament to body build, metabolic and other physiological factors, excess or deficiency of gonadal and other hormone stimulation, and homosexual behavior, and to such environmental influences as parent-child attachments, number and sex of siblings, sex of teachers, type of education, marital compatibility, and choice of friends or of occupations. It will be especially interesting to compare M-F differences in different cultures, and in the same culture at intervals of one or more generations. In short, the measurement of M-F differences will make it possible greatly to expand our knowledge of the causes which produce them.Our primary task has been to throw light on the meaning of the M-F score. For this reason we have presented only a relatively brief summary of the extensive experimental work which was necessary to bring the test to its present form, and have devoted the bulk of our volume to the relationships found to obtain between M-F score and other variables, including physique, personality traits as rated and measured, achievement, age, education, intelligence, occupational classification, interests, domestic milieu, delinquency, and homosexuality. It is hoped that the reader will thus be sufficiently impressed by the multiplicity of factors which go to determine an individual's score and by the complexity of interaction among them. In the interest of concreteness and in order to illustrate some of the major questions that arise in score interpretation, three chapters have been devoted to case studies. We believe that many of these will be of surpassing interest to the general reader as well as to the professional student of personality and temperament CHAPTER II ORIGIN OF THE M-F TEST The idea of developing a test of masculinity and femininity first occurred to the senior author in 1922 in connection with an investigation of intellectually superior children. One division of that investigation had for its purpose comparison of gifted and unselected children with respect to their interest in, practice of, and knowledge about plays, games, and amusements. Each of 90 such activities was rated three times by each subject; first for acquaintance with it, secondly for interest in it, and thirdly for frequency"with which it was practiced. There followed a list of 45 questions about experience or accomplishment in a wide variety of activities hardly to be classed as plays or games, such as " Have you ever cooked a meal ?" " Havfe you ever taken part in a play?" etc. Finally, there were 123 information questions designed to test the subject's actual knowledge about the plays, games, and other activities. (Examples: "A singing game is follow-the-l...