Education is an inseparable development element that influences a nation's socio-economic growth and its citizenry for a quality life. This study aimed to explore the supervisory practices by senior high school principals in Greater Monrovia, Liberia and the challenges faced during supervision. The study employed qualitative design and included 30 participants. Findings indicated that senior high school principals used supervisory practices such as inspection of teachers' lesson notes, punctuality, organized in-service training and inspection of classroom managerial skills of teachers. Notwithstanding these supervisory practices by school principals, the study found that supervision was impeded by lack of resources for teaching and learning, limited teaching staff, inexperience teachers, and improper attitudes by teachers and students.