Recent studies conclude that teachers are important for student learning but it remains uncertain what actually determines effective teaching. This study directly peers into the black box of educational production by investigating the relationship between lecture style teaching and student achievement. Based on matched student-teacher data for the US, the estimation strategy exploits between-subject variation to control for unobserved student traits. Results indicate that traditional lecture style teaching is associated with significantly higher student achievement. No support for detrimental effects of lecture style teaching can be found even when evaluating possible selection biases due to unobservable teacher characteristics. (Contains 9 tables.)