Psychological safety is the perception of individuals and how likely they are to share their ideas without feeling uncomfortable taking risks or vulnerable to criticism. While prior research has indicated that psychological safety is positively related to team performance and outcomes, research related to psychological safety in engineering teams has been less established. There is also a lack of comprehensive methodologies that capture the dynamic changes that occur throughout the design process. This is problematic because without this knowledge we cannot begin to answer the questions of what types of interventions may be useful for bolstering psychological safety in engineering teams, how these interventions might be delivered, or when these interventions would be most useful. In order to provide results to contribute to answering these questions, a study was conducted with 263 engineering students in 68 teams in a first-year engineering design class. The trajectory of psychological safety was captured for each team over five-time points in the engineering design process. This data was used to first identify how reliable and applicable the measure of psychological safety is for the longitudinal tracking of engineering design student teams as well as identifying factors that contribute to the building or waning of psychological safety in engineering student teams. The results of this thesis provide some of the first evidence on the reliability of psychological safety in engineering teams and offer insights as to how to support and improve team performance.