UM trailed the University of Connecticut, Dickinson College, Stanford and American universities, among others, while besting the likes of Harvard, Yale and the University of California, Berkeley.
UM earned 732 points out of a possible 1,000 in a review of everything from its curriculum to its waste, food, energy consumption and investments.
It's a roaring comeback for College Park, after only making 73rd in last year's "Cool Schools" list, which Sierra has been publishing for seven years now. UM had been ranked 20th in 2011, after not making the list at all in 2010 - though the University of Maryland Baltimore County came in 158th that year.
The only other Maryland campus to make Sierra's list this year was Frostburg State University, which ranked 98th, down from the 66th spot in 2012.
P.S. - Such rankings of campus sustainability don't insulate a school from criticism. Green Mountain College in Vermont - consistently rated greener than UM - provoked a furor last fall after announcing plans to slaughter a pair of oxen it used on the campus farm and serve the butchered animals to the students. School officials insisted the plan demonstrated the school's commitment to sustainability by producing its own food. But the uproar from animal rights activists prompted the college to euthaize one animal (said to be in ill health) and "retire" the other, without making meals of either.