We investigated whether motivation for same-sex sexual contact was related to mid-cycle peaks in estrogen levels (typically associated with ovulation) among women with consistent versus inconsistent patterns of same-sex sexuality. Twenty women (M age = 30 years), all of whom have been providing data on their sexual behavior and identities since 1995, completed daily diaries assessing sexual motivation and provided 10 days of salivary estrogen samples. During the 3 consecutive days on which estrogen levels peaked, women who had consistently identified as lesbian since 1995 (n = 5) showed increased motivation for sexual contact with women. This change in same-sex motivation was significantly smaller among women who consistently identified as bisexual (n = 7) and women who had given up their lesbian or bisexual identities at some point since 1995 (n = 8). Women who ascribed a role for "choice" in their same-sex sexuality also showed smaller increases in same-sex motivation. The findings suggest that women with consistent versus inconsistent patterns of same-sex sexuality might be experiencing different types of same-sex desires influenced by different factors.