The project aims to analyze the effectiveness of teachers and its determinants based on student-level achievement data from the German National Educational Panel Study (NEPS). The existing US literature typically operationalizes teacher effectiveness using teacher fixed effects from value-added models of student achievement, where the estimated teacher fixed effects serve as a proxy for teacher quality. They quantify the overall teacher contribution to student learning, including the impacts of observed as well as unobserved teacher traits. The US evidence suggests that variation in these measures of teacher quality can explain a substantial part of the overall variation in student achievement. It is yet unclear, though, whether such substantial effects are also present in other education systems; no equivalent estimates for Germany exist so far. A first key goal of the project is therefore to fill this gap by exploiting the longitudinal structure of the NEPS data to estimate value-added models of student achievement that include teacher fixed effects. Based on the estimated distribution of teacher quality, we can quantify the effects of having an “effective” teacher on student achievement, captured by the average increase in student achievement associated with a one standard deviation improvement in teacher quality. A particular goal is to compare our estimates with the available US evidence to investigate whether German teachers are more homogeneous in terms of effectiveness.