Thermodynamics is a core part of curricula in physics and many engineering fields. Despite the apparent similarity in coverage, individual courses in each discipline have distinct emphases and applications. Physics education researchers have identified student difficulties with concepts such as heat, temperature, and entropy as well as with larger grain-sized ideas such as state variables, path-dependent processes, etc. Engineering education research has corroborated some of these findings and has identified additional difficulties unique to engineering contexts such as confusion between steady-state and equilibrium processes. We are beginning a project that provides an opportunity to expand the interdisciplinary research on conceptual understanding in thermodynamics. This project has two goals: first, determine the overlapping content and concepts across the disciplines; second, compare conceptual understanding between these groups using existing conceptual questions from PER and EER. We present a review of PER and EER literature in thermodynamics and highlight some concepts that we will investigate.