Intensive care units (ICUs) provide care to the most severely ill hospitalized patients. Although ICUs increasingly rely on interprofessional teams to provide critical care, little about actual teamwork in this context is well understood. The ICU team is typically comprised of physicians or intensivists, clinical pharmacists, respiratory therapists, dieticians, bedside nurses, clinical psychologists, and clinicians-in-training. ICU teams are distinguished from other health care teams in that they are low in temporal stability, which can impede important team dynamics. Furthermore, ICU teams must work in physically and emotionally challenging environments. Our review of the literature reveals the importance of information sharing and decision-making processes, and identifies potential barriers to successful team performance, including the lack of effective conflict management and the presence of multiple and sometimes conflicting goals. Key knowledge gaps about ICU teams include the need for more actionable data linking ICU team structure to team functioning and patient-, family-, ICU-, and hospital-level outcomes. In particular, research is needed to better delineate and define the ICU team, identify additional psychosocial phenomena that impact ICU team performance, and address varying and often competing indicators of ICU team effectiveness as a multivariate and multilevel problem that requires better understanding of the independent effects and interdependencies between nested elements (i.e., hospitals, ICUs, and ICU teams). Ultimately efforts to advance team-based care are essential for improving ICU performance, but more work is need to develop actionable interventions that ensure that critically ill patients receive the best care possible.