Why do women outnumber men in study abroad?

The short answer is that no one really knows. The long answer appears to emphasize the curriculum typically studied (which tends to be in more "female" fields), the growing numbers of women in higher education more generally, the fact that parents are more concerned about safety for their daughters than sons (so less "independent" travel for women), and that many women are worried that if they don't travel in college, they won't get another chance until after their children are out of the house.

http://www.insidehighered.com/news/2008/12/04/genderabroad