This article describes a series of studies on teachers' attempts to modify the intensity and duration of their emotions, and how their emotions are expressed in the classroom. Among the important findings is that teachers practice emotion regulation because they believe it makes them more effective in management, discipline, and their relationships with students. Further, teachers are much more confident that they can communicate their positive emotions than reduce their negative emotions, and they use a variety of emotion regulation strategies, including preventive and reactive methods. These results stand in contrast to the fact that most pre-service programs give little emphasis to relationships among teachers' emotions, classroom management, and teaching practice. (Contains 1 table and 2 notes.)