Although teamwork is being integrated throughout engineering education because of the perceived benefits of teams, the construct of psychological safety has been largely ignored in engineering research. This omission is unfortunate, because psychological safety reflects collective perceptions about how comfortable team members feel in sharing their perspectives and it has been found to positively impact team performance in samples outside of engineering . Engineering team research has also been crippled by “snap-shot” methodologies and the resulting lack of investigation into the dynamic changes that happen within a team over course projects. This is problematic, because we do not know when, how, or what type of interventions are needed to effectively improve “t-shaped” engineering skills like teamwork, communication, and engaging successfully in a diverse team. In light of these issues, the goal of the current study was to understand how psychological safety might be measured practically and reliably in engineering student teams over time. In addition, we sought to identify the trajectory of psychological safety for engineering design student teams and identify the potential factors that impact the building and waning of psychological safety in these teams. This was accomplished through a 4-week study with 12 engineering design teams where data was captured at six time points. The results of this study present some of the first evidence on the reliability of psychological safety in engineering student populations. The results also help begin to answer some difficult fundamental questions on supporting team performance in engineering education.