In this contribution, we investigate links between teacher competence, teaching quality , and student outcomes in elementary science education . Students' conceptual understanding and interest were measured during two teaching units in a pre-post design (1070 students, 54 classes). Results show that teacher competence (pedagogical content knowledge, self-efficacy, and teaching enthusiasm) was positively related to students' interest; self-efficacy was positively related to student achievement. Three dimensions of teaching quality (cognitive activation, supportive climate, and classroom management), which refer to the actual teacher-student-interactions in the classroom, mediated these relationships. These results help illuminate the mechanisms behind the effects of teachers on student outcomes.