This article develops relational models leadership theory, which explains how shared cognition produces group-level leadership emergence effects. The theory proposes that contextual features present early in a group's life can cause members to quickly converge on one of two cognitive relational models for leadership. Some groups adopt an authority ranking model, in which leadership influence is consolidated in the hands of a few high-status members. Others adopt a communal sharing model, in which leadership is the collective responsibility of all members. A positive feedback loop develops between group members' relational model convergence and leadership emergence, such that members enact leadership in a manner consistent with their shared relational model and these interactions reinforce the model. The theory also identifies two types of "jolt" events that can radically shift group members' cognitions and actions related to leadership.