Students have the right to be taught by competent teachers who have a clear understanding of how students imbibe instructions and such teachers must be given appropriate resources in terms of tools to carry out the assignment. This article examines the effects of supervision and quality of teaching personnel on students' academic performance in the context of schools in a specific developing country context, that of Nigeria. Also this paper examines the differences in the effects of supervision and quality of teaching personnel on students' academics performance in the public and private secondary schools. It does so by testing a model of such effects using a set of data collected from a sample of Nigerian secondary school teachers. Analysis shows supervision dimensions to have strong effects on secondary school students' academic performance. Supervision had significant add-on effects to quality of teaching personnel in prediction of secondary school students' academic performance. (Contains 6 tables.)