This special issue aims to prompt reflection on the mutual contribution of attachment theory, on the one hand, and teacher-child relationship research, on the other, by bringing together conceptual and empirical contributions taking an attachment perspective on teacher-child relationships. In this introductory article, we contend that the teacher can be regarded as an ad hoc attachment figure with a safe haven and secure base function, although for most children the relationship with the teacher is probably not an attachment bond. Furthermore, we explain how attachment theory and research: (1) shape the way in which "high quality" teacher-child relationships are conceptualized and operationalized; (2) highlight the importance of teacher sensitivity to children's needs, as a central proximal determinant of relationship quality; (3) guide research hypotheses regarding the consequences of teacher-child relationship quality and the intervening mechanisms; and (4) inspire the development of interventions to improve teacher-child relationships.