It is growing increasingly evident that online learning is the future of K-12 education, both in the United States and the rest of the industrialized world. Improved technology, coupled with the perceived cost-effectiveness of online education, has resulted in growing numbers of states and K-12 school districts embracing “anytime, anywhere” education. Research on K-12 online education, however, has not kept up with its growth. This chapter explores three structural issues that are currently limiting online learning from being a viable alternative to K-12 face-to-face instruction in the United States: inadequate training of online K-12 teachers, issues related to accessibility for students with diverse learning needs, and the importance of structuring courses in a way that responds to the diverse backgrounds of K-12 students. Although this chapter is framed from an American perspective, largely because the vast majority of K-12 online learning occurs in the United States, future research on these issues is essential to K-12 online education in any context.