“Girl-on-girl” behaviour is portrayed as sexy, liberating, and edgy in contemporary popular culture, mass media, and public settings such as bars and parties. This study looked at the relation of women’s participation in public same-sex sexual behaviour (PSSSB), age, and sexual orientation (heterosexual versus some degree of same-sex orientation) with the following dependent variables: perceptions of PSSSB pressure, reasons for and feelings after engaging in PSSSB, sexual depression, sexual assertiveness, sexual self-efficacy, sexual locus of control, sexual monitoring, and use of PSSSB to explore sexual orientation. Of the 451 women (ages 19-40) who completed the online questionnaire, 54% reported having engaged in PSSSB. Most participants agreed that young women feel pressured to engage in PSSSB and listed media, popular culture, male friends, and peers as sources of this pressure. Exclusively heterosexual women who had engaged in PSSSB (n=100) reported significantly higher perceived social pressure, more subsequent negative feelings, higher sexual depression, greater external sexual locus of control, lower sexual assertiveness than all other participants, and lower scores on sexual self-efficacy than PSSSB women with same-sex orientations. Emerging adult, but not older heterosexual PSSSB women, had significantly higher sexual compliance scores. Heterosexual and same-sex orientation PSSSB women had the highest rates of sexual monitoring, and although their reasons for engaging in PSSSB were different, a majority of both listed alcohol and exploration as factors that contributed to their public girl-on-girl behaviour. Heterosexual women who had not engaged in PSSSB indicated the lowest rates of sexual exploration. Reasons for these differences are discussed. / Graduate