Abstract
Masturbation involving groups has been virtually unstudied. There is some evidence that a substantial percentage of heterosexual and homosexual men have participated in group masturbation as boys. Girls, who masturbate with lower incidence and less frequently than boys, appear to form pairs more often than groups for masturbation. At least 40 organized adult men's masturbation clubs exist worldwide. Probably many more small, informal male groups flourish less publicly. Adult women's recreational sex groups do not appear to focus on masturbation per se. A few mixed-gender adult masturbation clubs exist. Conjectures are given about participation by males versus females, number and characteristics of participants, and trends.