The dramatic effects that teachers have on students’ achievement are largely undisputed. Empirically, a number of studies have shown that the quality of teachers is strongly related to students’ performance. This study presents evidence on this issue with a sample of 400 students and 200 teachers from 40 purposively selected secondary schools in Ibadan metropolis in Nigeria. These schools were categorized into four as public elite schools; public non-elite schools; private elite schools and private non-elite schools. A composite measure of the quality of the teachers covering qualification, experience, patience, creativity, and communication skills was utilized. The students’ performance was measured by their scores in the two compulsory subjects of English Language and Mathematics in the general school leaving certificate examination. The empirical methodology combined descriptive and inferential statistical analysis. The results suggest that the observed variations in the students’ performance across the four categories of the schools are significantly explained by the differences in the quality of the teachers.