Want cognitively diverse teams? It’s not as simple as hiring more female technologists. When Etsy stopped poaching and started training junior women to be rockstars, more senior engineers–men and women–saw the company’s progressive policies and started calling.

In Silicon Valley today it’s not possible to hire more women simply by recruiting them. Good engineers today have their pick of jobs, and good female engineers are being stalked like the last antelope on the African veldt.

For Etsy, diversifying wasn’t just about good citizenship–it was vital to the product. Eighty percent of Etsy customers are female, but the company itself used to be known in startup circles as engineer-centric and something of a dude-fest: As of January 2011, the company only had three female engineers out of 47. Despairing, management gave up searching for senior female engineers and set about training junior prospects. Today, Etsy’s engineering team is 20 ladies to 90 guys, or 500% more women than two years ago.

In 2011 the company decided to make recruiting women a stated core value for the year, but by December, they had only added one female engineer out of the 40 technologists they hired, driving the gender balance down 35%. “This is over a year when we were saying it’s really important, we’re working really hard on this,” said Etsy CTO Kellan Elliott-McCrea, in a talk at First Round Capital’s annual CTO Summit. “Something wasn’t working. This was deeply broken.”

Etsy CTO Kellan Elliott-McCrea: ‘Something wasn’t working. This was deeply broken.’

Women hold just one quarter of engineering and computer-related jobs, and at many of the supposedly most innovative companies, the ratio is much much lower. There’s lots of embryonic efforts to get girls into coding and entrepreneurship, like Change the Ratio, Rails Girls, and Black Girls Code, but many are too far up the pipeline to help a company that’s hiring now.

Then there’s a chicken-and-egg problem. How are you going to pull in senior women candidates when they look at your staff and see all the women in support roles? How do you make a female engineer feel welcome when almost every single coder is a dude?

“Great women engineers are not only NOT looking for work,” says Elliott-McCrea, but also, they’re wary of being burned by the culture. If all they see is men, “there’s a decent chance, based on their experience, that your workplace is going to suck.”