In the present investigation has been under taken in order to study the teacher effectiveness of school teachers in Chennai and Thiruvallur Districts. Teacher Effectiveness of school teachers’ scale was constructed and standardized by Kumar and Mutha (1974) has been administrated to a random sample of 900 school teachers. It is found that teachers significantly differ in teacher effectiveness in respect of gender, place of school, level of teaching and they do not differ in teacher effectiveness in respect of marital status, age, type of management, years of experience and monthly income of teachers.