Research on teamwork has considered the effects of different types of feedback and information exchanged as teams coordinate their actions and has described team processes in terms of phases of task performance. Interpersonal communication processes represent the behavioral mechanism by which teams create shared mental models, but it is not clear how teams use and exchange feedback as part of these processes as they perform together. Using a 5-year-period, grounded theory methodology, we investigated how action teams exchange feedback to achieve teamwork. We examined the feedback process of three different elite French military teams. Our findings offer new evidence that action teams working in extreme/high stakes contexts use different types of feedback from multiple sources and that certain feedback sources are more relevant and certain feedback practices are more prevalent at certain stages. Specifically, throughout briefing, team task performance, formal debriefing, and informal debriefing stages, the teams we studied used information from multiple sources as they engaged in technique, reflexive, and socialization feedback practices. Teamwork was evident as the teams coordinated their action during recurring performance cycles. We use our findings to model the feedback process for teamwork and discuss implications for research and practice.