In the 2009-2010 academic year, women accounted for nearly two-thirds of the 270,600 American students going overseas. Indeed, the proportion of men studying overseas has remained the same--or flatlined, to put it less charitably--for more than two decades. Sending a broader cross-section of majors abroad has not made a dent in the gender gap because, it turns out, women in those fields study overseas at rates disproportionate to their numbers. From its inception, more than a century ago, study abroad has had a reputation as a female pursuit, the lasting image one of Seven Sisters students steaming overseas for a grand European tour of art and culture, a refining gloss for a marriageable young woman. "Women were sent overseas to be culturally educated ladies who could entertain their husbands' business partners," says James M. Lucas, of Michigan State University, who has written extensively about men and study abroad. "The mantra became that study abroad is feminized and a dalliance." Recent research suggests that the two sexes respond to different messages, and different messengers, when deciding to study abroad. Whatever the cause, the trend worries many in the field, who say an international experience has become even more valuable for students. Mr. Lucas, assistant to the dean for international academic student life at Michigan State organizes short study-abroad programs for incoming freshmen. He writes different letters to male and female students to promote the trips. Women get the "traditional" message, which highlights the cultural and experiential benefits of going overseas, while the letter to men "makes it sound more like a privilege," he says. "I tell them, 'This is how you are going to distinguish yourself at a big university and, later on, in a global work force.'"