Citing the size of the Gates Foundation, philanthropy experts applauded the change.
The Hewlett Foundation, which told The Times last fall that it invested purely to maximize profit, said it was now rethinking that strategy.
"The investment committee of the board has been engaged in a discussion of the topic for some time and will make their recommendations to the full board," Hewlett spokesman Eric Brown said.
The Packard Foundation has spent $150 million on program-related investments, and a committee of its trustees formed in September is examining other such socially responsible investment tools, Packard spokesman Chris DeCardy said.
The foundation plans to hire a chief investment officer, DeCardy said, who will be charged with leading "the foundation through social responsibility."
Lindblom and other social-investment advocates say that divesting from companies with socially harmful practices is usually not the most effective approach. Instead, he said, given the Gates Foundation's vast holdings and prestige, a well-conceived program of shareholder involvement could make it "a real force for change."
"We find that the right thing is nearly always consistent with long-term, sustainable profit interests," Lindblom said.
The Cummings Foundation, which has a $522-million endowment, advocates voting corporate proxies on social issues to pressure offending companies to improve their social responsibility.
The Ford Foundation, the nation's second-largest with about $11.5 billion in assets, votes hundreds of proxies annually.
Scott's statement said investment managers for the Bill & Melinda Gates Foundation Trust — a separate organization recently established to manage the charitable foundation's endowment — already votes stock proxies "to encourage good corporate governance."
"In some cases, we have voted a proxy against the management's recommendation because it was at odds with our core principles — including a shareholder proposal on AIDS that ran counter to our grantees' work in that area," Scott said.
Last May, the foundation had told the Chronicle of Philanthropy that it did not get involved in proxy issues.
Steve Gunderson, president of the Council on Foundations, a Washington-based nonprofit that counts 2,000 grant-making foundations and corporations as members, said the Gates Foundation was slow to recognize the importance of social investing for institutions that receive major tax benefits. But if the foundation now makes up for it, he said, the entire world of philanthropy could gain greater public trust.
"They have become the face of philanthropy for the country, if not the world," Gunderson said. "The move you saw today is the kind of socially responsible reaction that the Gates Foundation will consistently engage in because they recognize their impact on all of philanthropy."