The difference in the time it takes women and men to reach orgasm during foreplay and vaginal intercourse is greater than it is for masturbation. While, on the average, it takes women 10-20 minutes, it usually doesn't take men as long. Single men, on the average, take seven minutes. Married men take 14. But these are averages that include men who take a lot longer to reach orgasm as well as those who don't take nearly as long. Most men, in fact, take only two minutes after penetration. Interestingly, the first few orgasmic contractions for women and men happen at exactly the same intervals — 0.8 seconds. (That may be why some couples find simultaneous orgasm so compelling.) Men average four to six of them. Women, six to 10.

Although there are plenty of theories, we don't know for sure the biological reasons, if any, for why most women need more time than men to reach orgasm during sex play. But we do know some of the psychological and social reasons:

• Women's sexual and reproductive anatomy has been misunderstood throughout thousands of years of western and eastern history. Not until the latter half of the 20th century were women expected to understand their own sexual anatomy or to explore the ways they might experience sexual pleasure. Many women, today, don't know how to reach orgasm through masturbation or through partnered sex play. This lack of understanding can inhibit the sexual arousal and excitement needed to reach orgasm.
• Most women experience orgasm through clitoral stimulation. But in most women, the clitoris is positioned in such a way that it is often not stimulated during vaginal intercourse. So in cultures like ours, that place a high value on vaginal intercourse, many women do not receive sufficient clitoral stimulation to bring them to orgasm more quickly, if at all. In most kinds of partnered sex play — manual, body-rubbing, oral, anal, or vaginal — a man's penis is directly stimulated. This is often not true for a woman's clitoris.
• In cultures like ours, there are many reasons for women to feel sexually inhibited. Many women feel anxious about unintended pregnancy and sexually transmitted infection. They may worry whether they've picked the right partner or if their partner is faithful. And many women feel anxious about whether they should really enjoy themselves sexually. All of these concerns, and others, can lead to performance anxiety that reduces a woman's ability to relax and enjoy her sexuality.