Masturbation is a common sexual practice with significant variations in reported incidence between men and women. The goal of this study was to explore (a) the age at initiation and frequency of masturbation, (b) the associations of masturbation with diverse variables, (c) the reported reasons for masturbating and associated emotions, and (d) the relation between frequency of masturbation and different sexual behavioral factors. Participants were 3,687 women who completed a web-based survey of previously pilot-tested items. The results reveal a high reported incidence of masturbation practices among this convenience sample of women. Among the women in this sample, 91% indicated that they had masturbated at some point in their lives, and 29.3% reported having masturbated within the past month. Masturbation behavior appears to be related to a greater sexual repertoire, more sexual fantasies, and greater reported ease in reaching sexual arousal and orgasm. Women reported many reasons for masturbation and a variety of direct and indirect techniques. A minority of women reported feeling shame and guilt associated with masturbation. Early masturbation experience might be beneficial to sexual arousal and orgasm in adulthood. Further, this study demonstrates that masturbation is a positive component in the structuring of female sexuality.