This article, based on six years of participant observation, provides a close-up view of two learning communities in an urban elementary school. It provides a case study of both learning communities, laying out how teachers participating in them learned to respond differently to difficult problems and dilemmas, to change their language and approach in addressing students' learning needs, to raise teaching problems and issues with increasing candor, and to become not only less resistant to change but also more innovative. In fact, the article draws close-up portraits of how these two learning communities in a school serving the district's lowest socioeconomic student population became crucibles for transforming professional identities so that teachers began privileging professional judgment over technical skill, praxis (reflection in practice) over specific technical practices, continuous learning over expertise, inquiry over solutions, and innovation over implementation. Along the way, it provides a back-story of an administrator who set high expectations and conveyed political realities without provoking either passive compliance or outright resistance. In the background looms the power of the district's shifting leadership and policies to sustain or destroy these promising communities. (Contains 6 notes.)