Previous research indicates that women prefer orgasms triggered by penile-vaginal intercourse (PVI) as compared to those triggered by direct manual stimulation of the clitoris. However, for reasons that are not well understood, most women are unable to reach PVI orgasms as often as they desire. In addition, it is unclear why many women prefer PVI orgasms to those triggered by direct clitoral stimulation. This study developed a more precise measure of PVI orgasm frequency and evaluated key predictors of this frequency, including duration of intercourse, physical and psychological health, and partner traits with implications for either mating quality or relationship quality. The present study also measured PVI orgasm importance and investigated why it is important for many women. The sample consisted of 835 adult women with experience in PVI. Mean PVI orgasm frequency was 50%, with 39.4% of women never or rarely having PVI orgasms, 37.1% sometimes having PVI orgasms, and 23.5% almost always or always having PVI orgasms. As a median response, women believed that PVI orgasm was “very important” and perceived importance was correlated with orgasm frequency (r = .31, p < .001), as were reasons for importance. Duration of intercourse showed a linear relationship with PVI orgasm frequency, but this finding was qualified for women at the low and high extremes of the orgasm frequency distribution. Body esteem, anxiety during intercourse, exercise, and general pain predicted PVI orgasm frequency. Sensitive male traits, although valued by women even more highly than alpha male traits, showed notably weaker relationships with PVI orgasm than did male alpha traits. This is consistent with evolutionary theories of orgasm, and it supports the view that the female orgasm may function to favor some males over others in terms of sire choice. Clinical and theoretical implications of the present findings are discussed.