Open Educational Resources (OER) have saved students millions of dollars in textbook costs and greatly expanded access to a wide variety of educational materials for countless numbers of students and life-long learners. OER have also saved teachers time and effort by allowing them to reuse, modify, and build on materials developed by other teachers. After a brief discussion of OER and foundations of open licensing, this article presents a number of opportunities for libraries, particularly those situated at research universities. [A list of combined References and Notes is provided.]