By comparison, traditional venture capitalists might seek a return 10 times their investment.
Some impact investors such as DBL Partners have had strong returns by using a broader definition of 'social impact.' DBL considers its investments in electric car company Tesla Motors and Juicero, a juice company that raised $70 million in March, as having both financial gain and social impact.
"You can walk and chew gum at the same time," said Nancy Pfund, founder of DBL, which raised a $400 million fund last year.
Still, many of the high-profile Silicon Valley venture firms have steered clear of investing outside their comfort zone.
"Your impact could be bigger. Stop looking at the 60 mile (area)" of Silicon Valley, Youssef Chaqor, founder and general manager of Kilimanjaro Environment, which recycles used cooking oil into biodiesel, told an audience of investors and entrepreneurs.
Some venture capitalists are worried about emerging market risks, such as fluctuating currencies, military coups, disease and corruption. Others don't see enough profit.
Andrea Carafa, founder and CEO of art and music event coordinator ArtsUp, says he does not bother to tell Silicon Valley venture capitalists about the societal benefits of his startup.
"They don't care if you're a social impact company," he said. "They care about your profitability."