College textbooks are notoriously expensive. Students shelled out an average of more than $1,200 each for books and supplies in the 2013-2014 school year, according to the College Board. Texts in many basic subjects like introductory economics, biology, and statistics cost as much as $200. A two-year-old nonprofit is hoping to change that. OpenStax College, established at Rice University with philanthropic funding from the Arnold, Hewlett, Gates, Maxfield, and 20 Million Minds foundations, creates peer-reviewed textbooks covering content of the most popular college classes, and encourages professors to assign them so students can take advantage of the fact that these books are free online and low-cost in print versions. Each title covers all the topics taught in a standard course, in the usual order, but professors who want to instruct somewhat differently can also customize the text to match their lessons. Thanks to a $6 million grant from the Laura and John Arnold Foundation, OpenStax is now in the midst of doubling its offerings, with new textbooks in pre-calculus, chemistry, U.S. history, psychology, and other subjects on the way. The initial goal is offering free texts for the nation’s 25 most-attended college courses. Disrupting the textbook market isn’t cheap—each one costs more than $500,000 to create. But with strong donor support, and a new distribution deal with the National Association of College Stores, OpenStax is on the way to its goal of supplying 10 million students with free or low-cost textbooks.