Over the past decade, online courses and entire online degree programs have been made available, serving millions of students in higher education. These online courses largely have been designed and taught using the theoretical concepts and practical strategies of Asynchronous Learning Networks (ALN). During 2003-04, approximately two million learners were engaged in higher education via ALN, and online enrollments are expected to grow at a 20% annual rate during the next few years. The Sloan Consortium (Sloan-C) has worked to help institutions improve the quality of their online offerings, and research has shown that ALN is a viable alternative to classroom-based learning. This paper reviews online enrollment trends in higher education, describes the characteristics of online programs that have scaled successfully to meet increasing demand, identifies challenges impacting the continued growth of online enrollments in this sector, and outlines the opportunities for increasing access to higher education through scaling of online initiatives. (Contains 4 figures.)