Mary Hatch will be the first one to tell you that her gender helped her get into college.

Ms. Hatch, a freshman at the Massachusetts Institute of Technology and a graduate of Peters Township High School, said that although some of her female classmates might argue otherwise, "You got in here because you're a girl. All the girls did."

It's not that Ms. Hatch is down on herself or her fellow females: MIT still rejects 73 percent of its female applicants. But the school rejects 88 percent of its male applicants and still ends up with a student body that's about 57 percent male.

For students applying to college, Ms. Hatch embodies the upside for females: Schools that have a strong focus on science, computer science or engineering tend to give girls an admissions edge to even out the student body.

But in college admissions, gender can be a blessing or a curse. For schools with a liberal arts focus, the pendulum can swing toward males.

"By and large, it's easier for males to get into liberal arts colleges than it is for females," said Joanna Schultz, director of college counseling for The Ellis School, a private all-girls school in Shadyside.

The male advantage stems from the fact that during the past few decades, the overall percentage of males in college has shrunk. According to the National Center for Education Statistics, males make up only 44 percent of collegiate student bodies -- down from 58 percent 30 years ago.

Speculation on the reason for declining male achievement in school varies from biological to sociological to educational factors.

In an effort to even out the student body at the college level, some schools are highlighting their engineering programs or putting more "masculine" pictures on brochures in an effort to attract males. And sometimes, gender equalization comes from the admissions committee.

How often does gender come into play at liberal arts schools? A 2005 study by Sandy Baum and Eban Goodstein, professors at Skidmore College and Lewis & Clark College, respectively, attempted to answer that question.

In exchange for anonymity, 13 schools shared data on their applicant pools with the researchers. The study found that when the share of female applicants to the school was below the range of 55 percent or 60 percent, gender "was not a significant determinant."

When the percentage rose above 55 percent or 60 percent, as it does, for example, at many schools that were previously women-only, schools often try to correct for that gender disparity through admissions.

"It seems like there is some point at which if women are very dominant, then you start seeing a preference for men," said Dr. Baum.

Ms. Schultz, at Ellis, said that she frequently hears about liberal arts schools that favor males and has seen it herself sitting in on admissions committees.

"If all else is equal, they'll take a male," said Ms. Schultz. "Sometimes even if it's not equal, they'll take a male."

For Ms. Schultz, who has worked at Ellis for 29 years, it's a fact that she doesn't try to hide from her students. She counsels them that published admissions statistics refer to both males and females and that they'll need to be at the upper end of any aggregate numbers.

Ms. Schultz said one liberal arts school, which she declined to name, once presented her with data showing that admitted female students had SAT scores 150 points higher than admitted males.

But despite the disadvantages that Ms. Schultz feels her students face in the admissions process, she understands why schools do what they do. If they took gender out of the equation, she said, they might have students bodies that were 60 percent or 70 percent female.

"When I went to college, I wanted to go to a co-ed campus," she said. "If it had been 70-30, I would not have gone, and that's what many of our girls say."

For social reasons, then, what is essentially affirmative action by gender is generally less controversial than preferences given to racial minorities, legacies or athletes.

Ginny Maddux, director of college counseling at Shady Side Academy, said some of her high school students ask about male-female ratios when choosing a college. "It affects their social life," she said. "They want to know 'Am I going to go to school and never have a date?' "

Depending on which side the student is on, however, a gender imbalance might not be a problem. "I like the idea of there being more boys," said Ms. Hatch, the MIT freshman. "There's more to choose from."

For Mike Steidel, director of admissions at Carnegie Mellon University, relatively equal gender representation improves the educational experience, as well as the social one.

"We need to have women and men," said Mr. Steidel. "Women bring a different element -- they bring those points of view that make for a more electric environment."

Overall, CMU admits about 37 percent of the males who apply and 50 percent of the females. Its student body is about 60 percent male and 40 percent female.

Mr. Steidel said that for programs at CMU where women are underrepresented in the applicant pool, gender is "definitely a factor, definitely a consideration. ... We sit up straight whenever we find a great candidate who happens to be a woman."

Those programs include many of CMU's strongest specialties, like electrical engineering and computer science. On the flip side, men are underrepresented in the theater department, another of CMU's most highly regarded programs. In theater, Mr. Steidel said, admissions preferences can favor males.

He said that in either case, however, gender is just one of many nonacademic factors that admissions officers consider after they determine that a student is academically qualified.

By using gender in an informal way, CMU -- and other schools that factor gender into admissions -- avoids the constitutional problems that the University of Georgia faced in 1999.

That year, a female applicant successfully sued the school, alleging gender discrimination for Georgia's policy of adding a quarter-point to its "Total Student Index Score" for all male applicants.

But as long as schools are not using gender to fill anything that resembles a quota, their policies are probably constitutional, said Ken Gormley, professor of constitutional law at the Duquesne University School of Law.

And even at schools where gender is considered, counselors and admissions officers stress that it is just one piece of the puzzle.

"It's more of an art as opposed to a specific science," said Mrs. Maddux of the college admissions process. "There are so many things that colleges and universities look for."

First Published: February 15, 2006, 5:00 a.m.