This paper examines the relative contribution of teacher’s education, subject matter
competency and pedagogical practices to 6th graders mathematics achievement in Namibia at
the start of the 21st century. Drawing on the rich dataset collected by the Southern African
Consortium for Monitoring Educational Quality (SACMEQ) between 2000 and 2002, which
facilitates rich pupil and school-level controls, and using multilevel modelling to take into
account for the nested structure of the data, the study finds that teachers matter, but that their
competency or effectiveness was defined differently for high and low SES schools in
Namibia. In low SES schools, effective teachers had a high level of subject matter
competency, worked in schools with a higher average of years of teacher training and set
daily homework. In high SES schools, teacher training continued to be associated with
effective teaching, but what the teacher did in the classroom in terms of her practices became
more relevant. The significance of teacher training and subject matter competence was also
replicated in several other SACMEQ countries. These findings support the notion that
effective teachers should not only have a sufficient level of subject matter competency but
should also receive adequate teacher training in order to develop effective pedagogical
practices and contribute to student achievement.