An implication of the current research on self-regulation is to implement the promotion of self-regulated learning in schools. Teachers can promote self-regulated learning either directly by teaching learning strategies or indirectly by arranging a learning environment that enables students to practice self-regulation. This study investigates teachers' direct and indirect promotion of self-regulated learning and its relation to the development of students' performance. Twenty German mathematics teachers with their overall 538 students (grade 9) were videotaped for a three-lesson unit on the Pythagorean Theorem. Students' mathematics performance was tested several times before and after the observed lessons. A low-inferent coding system was applied to assess the teachers' implicit or explicit instruction of cognitive strategies (e.g., organisation), metacognitive strategies (e.g., planning), and motivational strategies (e.g., resource management). High-inferent ratings were used to assess features of the learning environment that foster self-regulation. Results reveal that a great amount of strategy teaching takes place in an implicit way, whereas explicit strategy teaching and supportive learning environment are rare. The instruction of organisation strategies and some features of the learning environment (constructivism, transfer) relate positively to students' performance development. In contrast to implicit strategy instruction, explicit strategy instruction was associated with a gain in performance. These results reveal a discrepancy between the usefulness of explicit strategy instruction and its rare occurrence in classrooms.