This article reports on a three-year ethnographic study with an experienced elementary science teacher and describes the role of her positive and negative emotions in constructing her science pedagogy, curriculum planning, and relationships with children and colleagues. Examples are offered of the different emotional experiences she related to her science teaching, and it is shown how insights from this research are useful and significant to researchers and educators who want to improve science teaching and learning. A conceptual and methodological framework developed by the author that is based on an interdisciplinary approach in researching emotions is presented. Finally, some implications of researching emotions for elementary science teacher education and science education reform are suggested. © 2002 John Wiley & Sons, Inc. J Res Sci Teach 39: 79–103, 2002