Eighteen U.S. colleges and universities have offset 100 percent of their greenhouse-gas emissions from electricity through renewable energy certificates.

Western Washington University, the University of Central Oklahoma, Evergreen State College, Concordia University Texas, and Unity College use 100 percent renewable energy to power their operations.

High school students and young adults have persuaded 200 U.S. colleges and universities to commit to paperless admissions processes by signing the online Students Plant the Seed petition.

New York University buys more green power than any other school in the country.

Thanks to a coalition of students, all 15 institutions in the University System of Maryland are conducting greenhouse-gas inventories. Some are converting buses to biodiesel and starting green building projects, with the goal of eliminating carbon emissions.

Climate change stresses agricultural systems, which could result in price spikes for crops such as hops and barley, the basics of a beverage close to many students' hearts. Cincinnati State Technical and Community College students connect those dots at the annual Save the Ales bash.

Indiana University dorm residents compete to conserve water and electricity in the monthlong Energy Challenge. This year students saved nearly 614,000 gallons of water and more than 400,000 kilowatt-hours of electricity.

After the student government refused to include a sustainability fee on the school ballot, the Student Environmental Center at Southern Illinois University gathered 2,500 signatures to put the fee up for a vote, and it passed overwhelmingly.

NOT LONG AGO small private colleges had a near monopoly on campus environmental initiatives in the United States. But today supersize public universities are nipping at the nimble, hemp-shod heels of those pioneers by adopting green building standards, expanding environmental studies programs, and converting fleets to zero-emission vehicles.

This represents a dramatic shift even from last year, when Sierra ran its first "Cool Schools" roundup and filled all but two of the top ten spots with private colleges. In the following pages, you'll find a diverse mix of institutions--from North Carolina's 850-student Warren Wilson College to Arizona State University, the country's second-largest school with 51,500 students.

The top schools earned points in ten categories: policies for building, energy, food, investment, procurement, and transportation; curriculum; environmental activism; waste management; and overall commitment to sustainability. A perfect score in every area would give a school 100 points.

Like every ranking system, ours is imperfect. To be sure, dozens more schools deserve praise. But after weeks of reporting and analysis, we're confident we picked the nation's environmental leaders.

That said, you might ask why the Eco League colleges and the University of California system--two environmentally proactive institutions--don't rank on this list. Schools in the Eco League consortium, which focuses solely on environmental studies, hardly play on a level field with schools that serve students in 150 degree programs. Meanwhile, the ten campuses of the UC system--neither wholly independent nor entirely unified--could not in fairness be compared as separate institutions. Sierra decided to feature them separately as "Shining Stars".

If you're excited about or frustrated with initiatives on your campus or convinced we've missed a great green school, you can vent or brag in the comments section. We hope you'll join the conversation--so we can make next year's list even better. —Lea Hartog

Illustration by Gregg Gordon/GIGART; used with permission.