People with extensive needs for support represent the last group of people routinely denied opportunities for literacy instruction. One of the major reasons for this lack of opportunity can be related to limited definitions of what constitutes literacy as a whole and reading and writing in particular. This article will explore the way in which definitions of literacy impact literacy opportunities for individuals with extensive needs for supports. We propose a set of core definitional principles and make explicit the assumptions underlying their inclusion. Our hope is that this will lead to a dialogue about how we define literacy and the implications this holds for the lives of people with extensive needs for support. Our work is based on the assumption that all individuals with extensive needs for support are fully capable of benefiting from literacy instruction and further that our field as a whole could benefit from a more optimistic and inclusive approach to literacy instruction.We conclude that the way in which we define literacy is powerful and essential to opening the final frontier of literacy opportunities to include people with extensive needs for support.