There is consensus that teachers matter for student achievement. However, still, research has had difficulties to provide reliable evidence for the effects of observable teacher characteristics, like qualification measures. The current study uses panel data based on register information from teachers and students to estimate effects of teacher characteristics on student achievement in mathematics and Swedish in Grade 6. Applying fixed-effects regression to a large sample of schools, we observed significant positive effects of several teacher characteristics. Having a teaching license was found to be one of the most important qualification measures, but also the teachers’ level of experience mattered for student achievement. The effects of teacher qualifications were generally stronger in mathematics than for Swedish.