This article offers description and interpretation for understanding the exercise of leadership in teacher collaboration. Data gathered in two urban high schools through observations and interviews were coded and categorized following Miles and Huberman's modified analytic induction technique. The analysis contributes to emerging theory on leadership through examining and reframing Heifetz's typology of technical and adaptive work to include nonrational properties evidenced in teacher teamwork. The findings forward questions, insights, and recommendations for practitioners about distributing leadership in efforts to reform teacher practice. (Contains 2 tables.)