UDL, a promising practice for all learners, is receiving attention in education. It provides a framework which supports learning by removing barriers and increasing access. But education innovations come and go. Will UDL be the next to go? This phenomenon of innovations coming and going has been discussed since the 1990s. Insufficiency of teacher training in learning, learning theory and motivation has been identified as one factor that may impact UDL’s sustainability. Educators with insufficient understanding of how students learn, how instruction and motivation impact learning, are more likely to take “. . . a ‘bag of tricks’ approach to teaching than a rational, theoretically driven approach to making instructional decisions” (Stevens, 2004, p. 391). Decisions to implement UDL through easy assignments from “the bag of tricks” or let students choose what they want to do may not be theory based and could negatively impact UDL’s success. This chapter considers the importance of making theory driven instructional decisions to effectively employ UDL with fidelity.