Studies in the Psychology of Sex, Volume I presents studies that explore the psychology of sex by addressing topics ranging from the evolution of modesty to the phenomenon of sexual periodicity, auto-erotism, and sexual impulse. The relationship between love and pain, sexual impulse in women, and sexual selection are also discussed, along with sexual inversion. Divided into four parts, this volume first deals with the evolution of modesty and variations in modesty among different peoples and in different ages. The reader is then introduced to the phenomenon of sexual periodicity, with emphasis on menstruation and its relation to ovulation; the various physiological and psychological rhythms; and the predominance of sexual excitement at and around the menstrual period. Subsequent chapters focus on auto-erotism and spontaneous manifestations of the sexual impulse; the link between love and pain; sexual impulse in women; and sexual selection. The book also analyzes the theory and nature of sexual inversion before concluding with an overview of relevant subjects such as homosexuality, castration, psychoanalysis, and marriage. This monograph will be of interest to physicians, psychologists, psychiatrists, criminologists, and educators.