NEW YORK - Women make only 80 percent of the salaries their male peers do one year after college; after 10 years in the work force, the gap between their pay widens further, according to a study released Monday.

The study, by the American Association of University Women Educational Foundation, found that 10 years after college, women earn only 69 percent of what men earn.

Even after controlling for hours, occupation, parenthood, and other factors known to affect earnings, the study found that one-quarter of the pay gap remains unexplained. The group said that portion of the gap is "likely due to sex discrimination."

"Over time, the unexplained portion of the pay gap grows," the group said in a news release.

Catherine Hill, the organization's director of research, said: "Part of the wage difference is a result of people's choices, another part is employer's assumptions of what people's choices will be. ... Employers assume that young women are going to leave the work force when they have children, and, therefore, don't promote them."

The organization found that women's scholastic performance was not reflected in their compensation. Women have slightly higher grade point averages than men in every major, including science and math. But women who attend highly selective colleges earn the same as men who attend minimally selective colleges, according to the study.

"The pay gap is not going to disappear just through educational achievements," Hill said.