Change.org, the buzzy online petition company that helped fuel public outrage over the Trayvon Martin murder case, has seen explosive growth over the last two years. Its founder, Ben Rattray, landed on Fortune’s 40 Under 40 list last year after the site logged 17 million users, a number that’s since grown to 25 million.

Today the startup added a new president and COO, Jennifer Dulski, who aims to take Change.org the rest of the way from influential startup to, she says, “a globally meaningful and loved brand.”

Dulski, age 41, comes to Change.org from Google , where she led project management for shopping and product ads. Before that, she was vice president and general manger of local and commerce at Yahoo, managing a staff of 500. She left Yahoo to lead the company that would become The Dealmap, an aggregator of local deals. The Dealmap, where Dulski was CEO, counted more than 3 million users of their site and mobile apps. The company was acquired by Google in 2011.

Being a woman in tech brings all sorts of challenges–even as women are making great strides. (America’s two largest tech companies, IBM and Hewlett-Packard , have female CEOs; Marissa Mayer runs Yahoo.)  While raising money as a startup CEO, Dulski recalls, she would occasionally walk into the women’s bathroom of a venture capital office in the afternoon to find all the seats still up –because no one had been in there all day.

Dulski was drawn to Change.org because the work is “meaningful,” she says. Change.org‘s impact on the human rights stage is wide-ranging. One petition pushed the South African Parliament to convene a task force to end the “corrective rape” of gay women. Another helped gather nationwide support for Trayvon Martin’s parents’ push for a police investigation into their son’s shooting. Another petition prodded Seventeen magazine to vow to stop Photoshopping out its models’ curves.

Rattray will continue as CEO of Change.org, working on outreach and business development. Dulski, as president, will focus on expanding  the operation, particularly by building up the product and design teams. “The fact that they’ve gotten as far as they have is incredible with a small team,” she says. Change.org, which is a hybrid for-profit company and charity,  makes money from non-profit advertising hosted on the site.

Dulski’s advice for women in tech actually could apply to anyone in any field. “If you want to feel more status in a meeting, just try putting your arm over the back of the chair,” she says. The gesture is a subtle power play. “When men put their feet up on the table and lean way back in their chair,” it’s the body language of status. “Women tend not to do that.”

Dulski adds: “Never apologize before you start to talk. You instantly lose your credibility.”