Research with children and adolescents shows that teachers are one of the agents from whom they receive mediation of their media use. However, little is known about teachers' mediation practice. This study aims to approximate teachers' practice with the concept of mediation by, firstly, systematizing a set of curricular media-related competences into the goals of maximizing opportunities and minimizing risks in youngsters' media behavior. Then, teachers' professional and personal characteristics are tested for associations with the mediation of risks and opportunities of students' media use. Data collected in a survey with 315 teachers in Germany were analyzed. Results of regression analysis show that most factors predicted both opportunities and risks in a similar way. Teachers are more engaged in maximizing opportunities and minimizing risks when they use information and communication technologies (ICT) more frequently, consider the respective competences important, engage in collaboration with colleagues, do not teach STEM subjects, and do not work in a Gymnasium. Having received ICT-related training was a significant predictor only of mediation of opportunities, while age was a significant predictor only of mediation of risks. Implications of the findings and how the concept of mediation can contribute to the development of teachers as media educators are discussed.