Despite research substantiating the idea that when team members voice ideas and suggestions their team can perform better, some scholars have warned that voice can also harm team performance. Yet, our understanding of when, why, and how voice can undermine team functioning is still limited. Attempting to address these research gaps, I integrate and build on threat rigidity theory and regulatory focus theory to propose that the reason why voice has the potential to undermine team performance is because it can trigger relationship conflict – and that prohibitive voice, as compared to promotive voice, has a greater potential to trigger relationship conflict, especially when team trust is low. I test this theory using a time-lagged, laboratory study with 87 teams, as well as a time-lagged, multi-source field study with 49 teams of U.S. Air Force officers. Across studies, I largely do not find support for my hypotheses. For example, opposite of my predictions, it appears that both promotive and prohibitive voice have either a non-significant or negative effect on relationship conflict; however, I find partial support for the hypothesis that trust moderates the relationship between prohibitive voice and relationship conflict. Despite these mixed findings, this research contributes to the voice, teams, relationship conflict, and trust literatures by empirically investigating whether voice can undermine team performance.