This study examined the sexual practices and function of midlife women by ethnicity (African American, Caucasian, Chinese, Hispanic, Japanese) and menopausal status. Sexual behavior was compared in 3,262 women in the baseline cohort of SWAN. Participants were 42 to 52 years old, premenopausal or early perimenopausal, and not hysterectomized or using hormones. Analysis used multivariate proportional odds regression. In our sample, 79% had engaged in sex with a partner in the last 6 months, and a third considered sex to be very important. Common reasons for no sex (n = 676) were lack of partner (67%), lack of interest (33%), and fatigue (16%). Compared with Caucasians, Japanese and Chinese women were less likely, and African Americans more likely, to report sex as very important (p < 0.005). Significant ethnic differences were found for frequency of all practices. Perimenopause status was associated only with higher frequencies of masturbation and pain during intercourse.