When asked to define UDL, many stakeholders split between focusing on the design process or focusing on the guidelines. Or, on focusing on teacher behavior or student decision making as the independent variable. Some propose that the attempt to focus on UDL as a univariate construct, resulting in "two-dimensional" views of UDL has been useful, but limited. In this talk, Moore will present his idea for moving UDL into a 3D perspective, and the implications this has for research, measurement, and practice.