Coursera Adds 17 Partner Universities, Including Brown and Columbia Coursera, a start-up online education company that has enrolled 1.35 million students in its free online courses since it began just five months ago, is now more than doubling, to 33, its partners, universities that will offer classes on its platform. All together, Coursera will provide more than 200 free "massive open online courses," known as MOOCs. The new partners include two more Ivy League institutions, Brown University and Columbia University; a liberal arts college, Wesleyan University; specialized institutions like the Mount Sinai School of Medicine; public research universities like the University of Florida; and more international schools like the University of Melbourne, Hebrew University of Jerusalem and Hong Kong University of Science and Technology. The caliber of Coursera's partners - Princeton, Stanford and the University of Pennsylvania were among the original partners - has given it credibility and cachet in higher education circles, so much so that some university presidents have begun to fret that it will reflect badly on them if they fail to sign on. "You're known by your partners, and this is the College of Cardinals," said E. Gordon Gee, the president of Ohio State, one of the new partners. It's some of the best universities in the country. Mr. Gee, whose university will offer two courses from its College of Pharmacy, said he had some concerns about giving away content with no revenue stream in sight. "That does keep me up at night," he said. We're doing this in the hope and expectation that we'll be able to build a financial model, but I don't know what it is. But we can't be too far behind in an area that's growing and changing as fast as this one. Columbia will start on Coursera with two engineering courses, according to the provost, John Coatsworth, but expects to expand to more courses in a variety of fields over the next year. The new courses will range broadly from Mount Sinai's three classes on systems biology to Berklee College of Music's four: introduction to guitar, introduction to improvisation (with the Grammy Award winner Gary Burton), introduction to music production and songwriting. "We've also been about expanding the reach of the college," said Debbie Cavalier, Berklee's vice president for online learning. We've always had some kind of free online offers, and we couldn't be more excited about this. Coursera's explosive growth shows no sign of leveling off. It enrolled its millionth student on Aug. 9; less than six weeks later, the student ticker on the Web site passed 1.35 million. The students come from 196 countries, with about a third from the United States and the next largest contingents from Brazil and India. A report from Moody's Investors Service last week predicted that the rise of MOOCs might help leading universities reach more students, bolster their reputation and eventually generate revenue from distributing content or issuing certificates. The report warned, however, that the growing popularity of free online courses could be a problem for small local colleges and for-profit institutions. Coursera was founded by two Stanford computer science professors, Daphne Koller and Andrew Ng, who are on leave. Another Stanford computer scientist, Sebastian Thrun, whose Stanford course on artificial intelligence last year had 160,000 students, is the co-founder of Udacity, another thriving MOOC company. Although Stanford remains one of Coursera's partners, the university is also experimenting with other approaches to massive online courses. Those include a newly developed open-source platform of its own, Class2Go, which will offer classes next month on computer networking and solar cells, fuel cells and batteries. "We really want to see what works," said John C. Mitchell, the recently appointed vice provost for online learning at Stanford. We've started out in one direction with Coursera - which is a great company, and it's great working with them - but it's not clear that the current mode of producing courses is where we're going to end up in five years. Many faculty members, he said, expressed a preference for offering online courses internally, on an open-source platform like Class2Go. Stanford has also offered a technology entrepreneurship MOOC on a third platform, Venture Lab. Ultimately, he said, different schools at Stanford may choose different approaches. A revenue stream may not be long in the making. Mr. Mitchell said he could imagine licensing courses, with other colleges paying a fee to use the material, just as they would for a textbook.