Teachers' professional vision is the ability to notice and interpret classroom interactions and may be considered an aspect of a teacher's competence. Despite research on school teachers, little is known about this competence in early childhood teachers. In this study, the relation between early childhood teachers' professional vision and their professional knowledge, work experience and quality of teacher-child interaction is investigated. In order to evoke professional vision, four video sequences of typical situations in daycare settings were presented. Professional vision was captured by the thinking aloud technique and rating-items, behavior was assessed by the Classroom Assessment Scoring System (CLASS Pre-K). Furthermore, a knowledge test assessing professional knowledge was applied. Professional vision was related to knowledge, work experience and quality of interactional behavior. The relations partially depend on the assessment method for professional vision. Results are discussed with regard to previous findings and implications for the methodology for assessing professional vision and for further research.