This document, based on a presentation from the 2018 UDL-IRN Summit, outlines the role of comprehensive research in the development of inclusive educational technologies. Increased availability of technology at home and in school has led to the proliferation of software and hardware designed to improve learning outcomes, but evidence of real impact is inconsistent. Part of the reason that educational technologies fail to effect substantial improvements in cognition and learning is a disconnect between intended product outcomes and real user experience. This is even more true for individuals whose needs differ from the average user. By documenting and analyzing the mechanisms through which users learn from educational technology, formative research efforts can inform more inclusive product development. Partnerships between researchers and developers form a foundation for thoughtful, evidence-based design that can channel educational technology efforts toward real learning improvements for all.