Stanford University, which has the fourth-largest endowment of any American college, will stop directly investing in coal mining companies. The university announced its limited divestment plan Tuesday citing decades-old investment principles that tell Stanford’s trustees to make as much money as they can but also give trustees the option to avoid investing in companies that “create substantial social injury.” The burning of coal is considered a major contributor to global climate change.

Stanford’s trustees and an advisory panel concluded “coal is consistent with this policy given the current availability of alternatives to coal that have less harmful environmental impacts,” the university said.

Other universities, such as Harvard University, have resisted pressure to divest from fossil fuel stocks, citing their obligation to make money and what little effect their investment decisions might have. Stanford’s endowment of $18.6 billion in the 2013 budget year is just over half of Harvard’s. It’s not clear how much Stanford has invested in coal companies currently.

“Moving away from coal in the investment context is a small, but constructive, step while work continues, at Stanford and elsewhere, to develop broadly viable sustainable energy solutions for the future,” Stanford President John Hennessy said in a statement.

Stanford did not prevent itself from investing in other fossil fuel stocks, including oil and natural gas. The burning of both gas contributes, to varying degrees, in the greenhouse gas effect. Oil and natural gas stocks have risen substantially over the past several years at the same time coal stocks have plummeted. Stanford said the new policy applies to investments it manages directly but that it would also encourage its external money managers to divest from coal too.