Enthusiasm is widely regarded as one of the most essential and desirable qualities and characteristics of effective teachers. This study is designed to assess the effects of teacher enthusiasm on student classroom engagement, learning goal orientation, and academic self-efficacy. Participants include 165 college students enrolled in basic communication classes. Results indicate that teacher enthusiasm is an effective predictor of student behavioral, cognitive, and emotional engagement, intrinsic goal orientation, and academic self-efficacy, but it is not a significant predictor of extrinsic goal orientation. Consequently, this study demonstrates the power of teacher enthusiasm in predicting and shaping students' behavior in the classroom.