The quality of instructional supportive interactions between preschool teachers and children positively relates to learning and developmental outcomes of children in institutions of early childhood education and care. The main focus of preschool teacher research, therefore, is on the impact of preschool teacher competencies in interaction quality. Previous research has shown that self-efficacy beliefs influence interaction quality. The present study examined this relation in a structural equation model that evaluated whether professional vision (conceptualized as "noticing" and "reasoning") of relevant interactional situations moderates the effect of self-efficacy beliefs on interaction quality in the domain of Instructional Support and whether preschool teachers' professional knowledge exerts influence on the model. Drawing on a sample of 120 German preschool teachers, analyses showed a moderating effect in the reasoning component of professional vision. Results offer new possibilities for the promotion of high-quality instructional interactions in German preschools.