Incorporating UDL principles allows faculty to create engaging and accessible online courses for diverse learners in higher education. This article demonstrates a systematic and iterative development and testing of a course about UDL designed with UDL principles in mind. Mixed methods data sources and analyses were used to explore (1) understanding, (2) use, and (3) perceptions of UDL by 132 graduate students across five semesters. In-service educators recognized the specific UDL guidelines and checkpoints built into the course and found first-hand experiences inspiring to implement UDL in their own teaching/service environments. Specific suggestions for universally-designed course elements are shared and discussed.