<p>Despite vast experience in face-to-face teaching, faculty and graduate teaching assistants (GTAs) still have a need to develop an online teaching skill set. Emergency remote teaching resulted in an avalanche of professional development opportunities. Post COVID-19, very few faculty can say that they have not been challenged by the need to teach online. Unfortunately, reacting to emergency situations in higher education comes at the expense of online pedagogy. Furthermore, instructors and GTAs prefer online resources over face-to-face training because of time constraints. This demonstrates a critical need to offer easy-access, on-the-job, self-paced, and theoretically-sound support to instructors who struggle with teaching online courses. This study reports on the results of a design-based research project to create and implement Purdue Repository for online Teaching and Learning (PoRTAL). Our guiding research questions focused on faculty and GTAs need for support, the affordances needed for PoRTAL, its effectiveness, and the barriers for implementation, replication, and escalation. The research process included four major phases and each phase comprised two development steps. The four phases were: 1) needs analysis and exploration, 2) internal evaluation, 3) expert evaluation, and 4) implementation. Each phase resulted in design principles to contribute to theory. Six design principles were identified: accessibility of open educational repositories, human performance technology principles for faculty training, attainable universal design for learning guidelines, online pedagogy vs technology training, content and design balance, and cultural and institutional barriers for project replication. Recommendations for practice and limitations of implementation are given.</p>