Co-written by Katherine Ullman.

It’s been a rough couple of weeks for women in STEM.

Most shockingly, Adria Richards, former developer evangelist at SendGrid, was fired after she publicly reported two men (one of whom was also fired) for making lewd jokes in earshot at a PyCon Conference. Richards has since received nasty messages for speaking out—including some that threatened her safety—in what is now referred to across the web as Donglegate (the jokes that began this incident were about dongles and forking; you get the idea).

Likewise, women game developers were shocked at an after party for a separate tech conference—this time the GDC in San Francisco—when they found that the party hosts had hired scantily clad women dancers to sashay on stage.

And that’s not all. Elise Andrew, a blogger in Canada who kept a low profile while running a very popular all-about-science Facebook page, promoted her new Twitter handle (which included her name and photo) to her Facebook fans. The response? Many were shocked that she was a woman. “Is this really 2013?” Andrews asked on Twitter.

The STEM fields are notoriously chilly for women. A new study by Corinne A. Moss-Racusin and colleagues found that science faculty rated men applying for a lab manager position as more hireable and competent than women with the exact same qualifications. A 2008 study by the Center for Work-Life Policy found that while 41% of highly qualified scientist, engineers, and technologists are women, 52% of these women quit their jobs around their mid-to-late thirties. The authors cite hostile workplace culture (like some of the recent incidents described above), long hours, and low expectations of career advancement as the main reasons for female attrition.

A third study from 2011 suggests that the exclusion of women in STEM may start even earlier. The study, by Danielle Gaucher, Justin Friesen and Aaron C. Kay, found that advertisements for male-dominated jobs—like many of those in STEM—contained a greater amount of masculine words (like dominate and competitive) than female-dominated positions. Women, after reading advertisements for male-dominated roles, were more likely than men to feel that they would not belong in these positions and found them less appealing. This pattern is perfectly illustrated by the posters that were at one time tacked up around Stanford University’s campus: “Want to bro down and crush some code? Klout is hiring.”

This chilly climate for women is an open secret. Said Etsy CTO Kellan Elliott-McCrea, “there's a decent chance, based on their experience in industry, that your workplace is going to suck” for women, making it hard to recruit women and increase diversity. Rather than focusing on recruiting senior women, who continued to flock to more gender-balanced tech departments, Etsy, in partnership with 37Signals and Yammer, paid for junior women to attend a three-month training program in New York City. As a result, Etsy has increased the number of women engineers by 500%. They now make up 20% of their department.

Etsy’s strategy addresses a key issue: the problem of reaching critical mass, so that a few women don’t feel out of place in a sea of men. To quote Jocelyn Goldfein, director of engineering at Facebook: “The reason there aren’t more women computer scientists is because there aren’t more women computer scientists.”

Women in STEM sometimes feel they stick out like a sore thumb, but that’s not the only problem. Recently, Joan’s project interviewed 60 women of color in these fields, describing the four basic patterns of gender bias and asking, “Any of that sound familiar?”

It did. All 60 scientists reported at least one of these patterns. One scientist explained her experience with the Prove-It-Again! pattern, which occurs when women have to provide more evidence of competence than men in order to be seen as equally competent. She recalled that, back when she was a student working in a group, her contributions fell on deaf ears. “And it wasn’t until the professor came around and said, ‘Are you guys listening to what [she] is saying?’ where it hit home to me that, you know, it didn’t matter what I was saying. But, it was just the fact that it was coming from my mouth.”

Several women in Silicon Valley reported that women get “the job but not the title,” and that they’re told over and over again that they are “not ready” for promotion—even, in one instance, where the woman in question had actually been doing the job in question.

Another STEM academic found that even students questioned her competence. “I have always had the impression when I start a class, a course, it is always an uphill kind of battle. I get the impression that students don’t believe that I know what I’m supposed to know.”

One scientist felt that even hard data—in the form of student evaluations— that proved her competence was brushed aside. “Even when I get really good evaluations, then the next thing that follows is ‘Well, you’re an easy grader, and so that must be why,’” she said.

And this was only one of the four patterns of bias. Joan’s impression by the time she finished the interviews: what’s amazing is not that there are so few women in science, but that there are any. What recent events and the 60 interviews show is that the STEM fields are filled with both overtly hostile and subtly discouraging hurdles that keep women down and ultimately push them out.

We keep hearing that STEM fields hold the jobs of the future; let’s give women a chance to “lean in” to them.