This article explores the impact of the No Child Left Behind Act (NCLB) on the behavior of teachers and school leaders, specifically the centralizing, standardizing tendencies of the legislation, and juxtaposes their reactions to the types of teaching and leadership required to lead 21st-century schools. The authors argue that the isomorphic behavioral responses to NCLB conflict with the pedagogical and leadership behaviors of the 21st-century schools movement. The authors conclude that unless modifications are made to the legislation, teachers and school leaders are unlikely to exhibit or promote the types of pedagogical skills, knowledge, or leadership envisioned by advocates of 21st-century schools. (Contains 1 table.)