This past Sunday, March 8, women and men throughout the world marked International Women’s Day with marches and speeches calling for gender equality.

The day is not well known in the United States, even though it originated here. It was first celebrated as National Women’s Day in 1909 to commemorate a strike the year before by 15,000 New York City women garment workers seeking equal pay, improved working conditions, the right to vote, and a ban on child labor.

In the years that followed, many of these goals were achieved. Laws passed during the Progressive Era took on sweatshop conditions and virtually eliminated child labor, and in 1920 American women earned the vote.

But the problem of unequal pay persists.

According to a report by the American Association of University Women, in 2013 the average American woman worker made 78 cents for every dollar earned by a man. The pay gap is larger for many women of color, with African American women earning 64 cents and Latinas earning just 54 cents for every dollar earned by white men.

What can we do to close the gender pay gap? Improving women’s access to well-paying jobs can help. Industries with high concentrations of science, technology, engineering, and math (STEM) workers hold out particular promise given their continued growth and higher wages for those with sub-baccalaureate training as well as four-year degree holders. But women—and especially women of color—are significantly underrepresented in STEM fields. For example, according to the Bureau of Labor Statistics women comprise almost half of the U.S. workforce but hold 35.2 percent of web developer jobs and just 19.8 percent of software developer jobs.

As I’ve explored in past blogs, organizations like the Ada Developers Academy and General Assembly are working to increase the number of women pursuing these and other lucrative tech-oriented careers. Similar efforts in other advanced industries can help more women take advantage of the wage premium that STEM-oriented careers confer.

But even with higher-paying careers, many women may still fall short because the gender pay gap also exists within occupations. Some argue that these differences reflect life choices made by individual women rather than evidence of systemic discrimination, but research suggests otherwise. Natalie Kitroeff and Jonathan Rodkin at Bloomberg Businessweek found that “high-achieving women are paid less than men even when they have similar levels of experience and are in the same fields.”

Professor Adam Grant of the Wharton School and Facebook COO Sheryl Sandberg recently wrote about how gender stereotypes among men and women persist even when people are aware of them. Recognizing implicit bias is an important first step, but we also need to counter our unconscious attitudes and the effects they have on society.

Of course, changing attitudes will take time. In the meantime, increasing women’s opportunities for careers in STEM fields would be a big step forward in the march toward gender equality.