Research suggests that teacher expectations can predict changes in student achievement and behavior. This Digest discusses the Pygmalion effect, or the idea that one's expectations about a person can eventually lead that person to behave and achieve in ways that conform to those expectations. Many teachers believe that they can judge ahead of time how certain students are likely, over time, to achieve and behave. The basis of a self-fulfilling prophesy (SFP) is that once a student has been pegged ahead of time, the chances are increased that a teacher's treatment of the student will help the negative prophecies or expectations come true. SFP can work to the detriment or benefit of the student, depending on the type of predictions and expectations. Teachers form expectations and assign labels based on such characteristics as body build, gender, race, ethnicity, name, attractiveness, dialect, and socioeconomic level. Different expectations lead to different treatments. Teachers convey expectations using four factors: climate, feedback, input, and output. The four factors can better be controlled if teachers are more aware that they are operating in the first place. Even if teachers do not truly feel that a student is capable of greater achievement or improved behavior, they should at least act as though they hold such heightened positive expectations. (Contains 14 references.) (SM)