For six decades, Bruce Tuckman's model of group development has given leaders a reliable map for a messy process: turning a collection of individuals into a functioning team. Teams form, they storm, they eventually norm, and if they are fortunate, they perform (Tuckman, 1965). The model has proven durable because it describes something true about human groups regardless of industry or era. What has changed is the composition of the team itself. A growing share of leaders now