Schools strive to educate fully every child who walks through their doors. Yet many schools find themselves burdened with large numbers of struggling learners who have not yet acquired the necessary foundation skills to successfully master the curriculum. Principals can draw on a large number of research-based strategies developed within the past two decades to help their school close the learning gap for struggling students. However, they should recognize that this growing knowledge base about effective interventions might also present a potential pitfall. Teachers might easily feel overwhelmed when asked to change their instructional routine to incorporate "best practices" in intervention. However, they will generally be less resistant to adopting more inclusive teaching strategies if they understand the unifying "big idea" that underlies these intervention strategies. This article describes one such "big idea" for accommodating diverse learners: the Universal Design for Learning (UDL). The philosophy that drives UDL--that "designing for the divergent needs of special populations (in classrooms) increases usability for everyone" (CAST 2003)--embraces several principles: (1) Children with learning or physical disabilities do not represent a distinctly different category, but instead fall "long a continuum of learner differences" (CAST 2003); (2) Educators are most successful when they adjust content and delivery of instruction to maximize success for "all" students, rather than concentrating on the needs of the most challenged learners; and (3) Instruction should not be tied to a sole source of information (e.g., textbooks), but instead ought to incorporate multiple resources, including digital materials, to illustrate key concepts and reinforce learning.