This study presents a model of Transformative Professional Development (TPD) for use in sustained, collaborative, professional development of teachers in urban middle school science. TPD focuses on urban science teacher change and is responsive to school climate, teacher needs, and teacher beliefs with the intention of promoting change in practice. In this study, TPD was used to meet the needs of individual teachers and the collective needs of schools in reform efforts. The experiences of the eight teachers engaged in this process of professional growth, including their changes in practices and beliefs, provide the focus of this paper. Findings in this study revealed that through the use of TPD, participants in this study improved science teaching effectiveness and began to transform their negative school climate and create positive classroom learning environments.