These days, the seats in college lecture halls are filled more frequently by female students than their male counterparts.

Women now make up 56 percent of the college population -- and that number continues to rise. Within ten years, three million more women than men could be attending college.

But this growing trend only tells half the story. While female students are the majority, males continue to hold more decision-making administration positions.

Where did the guys go?

Thirty years ago, male students were the majority on college campuses. Because traditionally, men were the family breadwinners, college was the path to career advancement and higher salaries.

But during the feminist movements of the 1970s, more girls sought career paths and enrolled in college to pursue a degree. By the mid- 1980s, more women than men were attending college.

At the same time, there was an unexpected drop in the number of boys applying to college -- a decline that has continued, baffling educators. No one can pinpoint the exact reason for the trend, although researchers have a number of theories.

According to the National Center for Education Statistics boys drop out or are expelled from school in higher numbers than girls. And male students are three times more likely to be enrolled in special education programs.

Author Christina Hoff Sommers attributes the drop to early stereotyping of boys as "too aggressive" and "non-academic." In her book, The War Against Boys, Sommers writes that many boys don't receive enough social support and mentoring to become straight-A students and therefore become disinterested in higher education.

Still others point to the growing number of men seeking jobs in repair, construction, technology and other areas that often don't require a four-year degree but promise a good salary.

Reverse gap behind the scenes

Along with the number of women attending college, more women can be found working behind the scenes as professors and administrators. Today, women account for 20 percent of college presidents, heading up schools such as the University of Pennsylvania, Princeton University and Brown University.

But women still face many challenges in higher education. A recent survey by the Council for Advancement and Support of Education said men still hold more of the upper management and decision-making positions at colleges and continue to earn higher salaries.

While women earn a higher percentage of bachelor's and master's degrees, they earn fewer doctorate degrees than men. There are also fewer women in many careers, including math, engineering, science and computers.

Women's advocacy groups like the American Association of University Women are pushing for colleges to make these issues a priority, but the focus for many schools still centers on recruiting more men.

Attempts to attract more male students

To increase male enrollment, schools such as Austin Peay in Tennessee have formed partnerships with male mentoring groups to encourage younger students to aim for college.

Other schools, such as Dickinson College and DePaul University, have modified their recruiting and admissions policies, sending out extra mailings to boys and paying close attention to male candidates. However public universities, face legal challenges to recruiting males.

Last July the University of Georgia lost a lawsuit filed by female students because of an affirmative-action policy that favored boys. Junior Shanna Norris voiced a common frustration: "It's not fair that a boy would get extra weight (in the admissions index) over a girl, but it would be better if there were more boys on campus."

Predictions for the future

The effect of larger female populations at colleges could register some noticeable changes, including the types of courses or programs that are offered. The influx of female students has already led to Women's Studies and more diverse classes and programs. As the proportion of women grows, schools might make similar additions.

And if women continue to make up the college student majority, there could be more pressure to hire women in decision-making positions.

Of course, schools must also confront the question of how social life on campus will evolve. Economist Andrew Sum believes a continuing decline in the number of college-educated men will mean that women who expect to marry a man with a similar education background will face a "marriage squeeze" that he sees as a serious economic and cultural problem.

"The choices for younger women will be more constrained than they were 20 years ago," Sum said in an ABC News interview.

Ultimately, the greatest challenge for colleges is to address the gender gap in ways that ensure that both boys and girls have equal access to opportunity in the halls of the nation's universities.

--By Raven Tyler, NewsHour Extra