This study examined the supervisory practices of school heads in Nigeria schools. It investigated the influence of headship supervisory practices on teachers’ job effectiveness. The study adopted descriptive survey research design. The population for the study comprised all public schools heads and teachers in a state. The sample comprised 30 heads and 450 teachers. Using stratified random and purposive sampling methods, 5 schools were selected each from the 6 Local Government Areas in Ondo State. From each school, 15 teachers and their head teacher were randomly selected. Two validated instruments titled “Headship Supervisory Practices Questionnaire - (HSP-Q)” and “Teachers’ Job Effectiveness Questionnaire - (TJE-Q)” were used for data collection. Data collected were analyzed using percentage, mean and multiple regression analysis. The results showed that supervision of classroom instructions, teachers’ attendance during lessons, supervision of lesson notes, students’ academic progress, and teacher’s development and trainings were all performed by heads in Ondo State secondary schools. The results further showed that up to 72.4% variance in school effectiveness can be attributed to the variations in headships’ supervisory practices. The study concluded that the combination of the headship supervisory practices significantly influence teachers’ job effectiveness
