Teams are complex, dynamic systems made up of interdependent members working toward a shared goal; but teamwork is more than working together as a group. Teamwork is a multifaceted phenomenon that allows a group of individuals to function effectively as a unit by using a set of interrelated knowledge, skills, and attitudes. Effective teamwork is marked by cooperation, communication, coordination, conflict management, coaching, and shared cognition among team members. The most effective teamwork leads to team performance gains that are greater than the sum of each individual member’s effort. These performance outcomes re-inform the teamwork process, thus creating a recursive feedback loop that drives team development and guides future performance. Along with performance outcomes, individual- and team-level changes incite learning and allow teams to adapt to the dynamic systems in which they exist. With each development cycle over time, teams learn how to maneuver their environment and allocate their resources to reach performance goals with more efficiency. There are many external factors that can influence this process, including organizational characteristics, situational demands, and team training interventions; as well as internal factors that emerge and evolve over the life of the team, such as shared mental models and psychological safety. Although teamwork is a complex phenomenon with many moving parts, a strong body of research guides practitioners in leveraging its influence on organizational effectiveness.