Women are heading to business school in larger numbers than ever before, and at younger ages to boot. But how much are women gaining from the degree? 

By Elizabeth G. Olson, contributor

FORTUNE -- More women than ever are earning graduate business degrees, and at younger ages than ever before. But it's unclear whether these women are gaining much from the degree, with persistent wage gaps between men and women who have the same business credentials and work experience.

Last year, almost 106,000 women -- the highest number ever -- took the GMAT, the standard admissions test for entry to MBA programs and other business graduate programs, according to the latest figures from the Graduate Management Admissions Council (GMAC), which owns the test. And the majority of test-takers between June 2009 and 2010 were 30 years old or younger.

In addition to MBAs, more women are pursuing graduate business degrees in disciplines like finance and accounting, GMAC found in its 2011 report.

Many of the younger female students are pursuing degrees full-time, such as Jessica Dillon, 29, who worked for seven years after college, at Fannie Mae and Capital One Bank (COF). She will graduate from Georgetown University's McDonough School of Business next year.

"You have to think about your return on investment," she says of her decision to earn an MBA. "Business school is expensive and you want to see that return at an earlier point in your career.  More