This article describes how two coaching models were utilized in an attempt to assist Jonathon, an experienced teacher who had been teaching science for only two years, to improve his science teaching. Because of the numerous difficulties that Jonathon encountered in planning and implementing the science curriculum, school administrators requested assistance from several science educators from a university near the school. In order to assist Jonathon, two coaching models were used over a period of approximately six months. In the first coaching program two high-school teachers were coached by three science educators from the university. In the second coaching program the teachers coached one another. Neither program was successful in improving Jonathon's teaching in the intended manner. The major impediments to change were Jonathon's beliefs about teaching and learning and his relatively poor knowledge of the science content he was to teach. The findings of the study suggest that the coaching interventions require teachers to analyze teaching, reflect on practice, and consider alternative approaches to teaching and learning. Involvement in the coaching programs provided Jonathon with a foundation of knowledge on which sustained improvements in teaching might develop in the future.