How children’s development is shaped by Early Childhood Education and Care (ECEC) classrooms and especially by teacher–child interactions in those settings is a major issue in research and politics, which has been researched for several decades. This book investigates this important topic by raising three overarching questions: (1) What are ‘good’ teacher–child interactions and how they can be measured? (2) Which individual and/or contextual aspects are associated with teacher–child interactions? (3) What is the impact of teacher–child interactions on the development of children's competencies? The book ties in these fundamental questions with educational research by bringing together international studies from interdisciplinary backgrounds and presenting current research on the characteristics, predictivity, dependency, and methodological issues of teacher–child interactions in ECEC classrooms. The considered studies conducted in Australia, Austria, Finland, Germany, Greece and Portugal each aim to enrich the scientific discourse and provide fruitful implications for policy and practice. This book was originally published as a special issue of the Research Papers in Education journal.