Teaching quality is known to be critical for students’ education and life prospects in developed countries. However, little is known about how teacher quality affects student learning in Africa. This paper presents the first estimates of teacher value-added from an African country, using data from a school-based RCT in northern Uganda. Exploiting the random assignment of students to classrooms within schools, the authors estimate a lower bound on teacher effects. A 1-SD increase in teacher quality leads to at least a 0.14 SD improvement in student performance on a reading test at the end of the year. Shifting teachers from the 10th to the 90th percentile of quality increases performance by 0.36 SDs – comparable to the most effective education interventions conducted in Africa. The results also suggest that an increase in teacher quality can make other education interventions more efficient.