Science teaching environments are social environments, and teachers' emotions interact with their science teaching in powerful ways. To value the teacher is to value the whole person, not just the intellect. In this paper, a theorization of teacher emotion in science teaching is developed which illustrates the role of emotion in establishing and maintaining self-esteem in science teaching situations. From the standpoint of social-constructionist theory of emotion, it is argued that emotion is a social construction within social relationships. Arising from this view, are the emotions of intellectual excitement, frustration and shame that play a key role in the development of self-esteem. The dynamics of these emotions, in the context of experiences of success and failure, may dispose teachers to act positively or negatively towards science teaching. The theorisation developed is illustrated in the emotional experiences of an elementary school teacher in an early childhood science classroom. These experiences indicate that emotion is constitutive of teaching, and merits greater consideration in science teaching.