In this resource, we review 125 studies published between 2000 and early 2019, that investigated the use of UDL in early childhood through postsecondary education settings. Highlights of our results include the finding that basic conceptualizations of UDL vary in significant ways, affecting the possibility of drawing conclusions about its impact and efficacy. UDL research is being disseminated to a variety of audiences, but is associated most frequently with special education. Research about UDL has increased and research quality has improved.