What started as an employee recruitment campaign has become a social media movement for women aiming to break stereotypes in the tech industry.

Using the hashtag #ILookLikeAnEngineer, thousands of women have tweeted photos of themselves with explanations of the work they do as engineers.

The hashtag caught fire over the weekend when Isis Wenger published a post on the website Medium about being featured in an ad campaign for OneLogin, the company she works for. The ad attracted much more attention than Ms. Wenger, who describes herself in the post as an “extreme introvert,” anticipated.

She typically doesn’t put a lot of thought into advertising and didn’t expect others would, Ms. Wenger said in an email. Many of the responses were positive, but several expressed disbelief that the ad accurately portrayed what female engineers look like.

“People generating discussions about whether or not I really was a platform engineer for OneLogin were also rather shocking,” she said.

Ms. Wenger said she had received “almost overwhelmingly positive feedback.” She has recruited collaborators to create a location-based app that will allow people to share personal stories about diversity issues in technology, she said.

Already, thousands of people have responded. At the end of her post on Medium, she encouraged those who identified with her message to use the hashtag. According to the social analytics website Topsy, the hashtag has been tweeted about 50,000 times over the last seven days.

Gender disparity and sexism in science, technology, engineering and math, known as STEM, have gained mainstream attention recently.

Ellen Pao’s gender discrimination lawsuit against the venture capital firm Kleiner Perkins Caufield & Byers thrust the issue into the spotlight, although the suit was unsuccessful. In June, comments by the Nobel laureate Tim Hunt asserting that women are distracting in the lab set off a social media campaign in which female scientists posted photos of themselves in the field with the hashtag #DistractinglySexy.

Data from the Computing Research Association shows the disparity starts in college, where about 12 percent of computer science and computer engineering degrees were awarded to women in 2011.

Continuing into the work force, women accounted for 26 percent of STEM jobs in the same year, according to a survey from the Census Bureau.

Tracy Chou, a software engineer at Pinterest, highlighted in a Medium post the need for a company-by-company breakdown of the numbers to give a clearer picture of today’s industry.

“It’s hypocritical that the tech industry is so built on open-sourcing things,” Ms. Chou said in an interview, “but in terms of what we could do for increasing diversity or building a more inclusive workplace, there’s none of that sharing going on.”

She started tracking the number of female software engineers and has information for more than 200 companies. A majority have staffs that are less than 50 percent female, and 30 companies have no women, according to her findings.

Several companies have been forthcoming with their data and have vowed to address the issue. Google started a program called Made With Code last year to bolster the female tech community and released a diversity report on its staff. Other tech giants, like Facebook and Amazon, followed suit in publicizing their numbers. But when those reports came out again this year, little progress had been made.

Ms. Chou has a few suggestions. But first it helps to identify the problem, which she said has two parts: One is in the education pipeline and another is in retaining female engineers once they get into the industry.

“The thing that companies can do right is make their workplaces more inclusive,” she said.

Pinterest is partnering with Paradigm, a firm that helps companies recruit diverse candidates, to test interviewing techniques and address barriers of entry and retention — an initiative called Inclusion Labs. The company has also set hiring goals to increase the percentage of female engineers to 30 percent from 19 percent by 2016, she said.

As for the social media campaign, Ms. Chou said she thought the photos and stories from women in the field would encourage aspiring engineers.

“I think it will be a good resource for people who are considering going into the industry and don’t feel like they necessarily fit in right now,” she said.

Ms. Wenger said she hoped her experience would be useful to others.

“It surprised me how receptive my manager was when I was first explaining to him detailed stories of unfavorable encounters I’ve experienced,” she said. “Most people lack the awareness and insight into the hurdles that other people jump through.”

The hashtag, Ms. Wenger said, “seems like it is long overdue. Instead of dwelling on any negativity, I’m focusing my energy on what I can do to help things improve.”