This chapter argues that the accounting literature in general and the accounting education literature in particular has under-invested in theory. The few theories that we officially believe are in use but are used quite poorly. Many theories that could be used are not used at all despite the promise that they appear to hold. Accounting education would be better understood if more of an effort was made to bring theory to the table in a variety of ways. [For the complete volume, "Advances in Accounting Education: Teaching and Curriculum Innovations. Volume 28," see ED674684.]