In a context where the role of the teacher and teacher education are undergoing considerable change, the role of educational psychology in teacher preparation is discussed within a new framework. Educational psychology is now perceived as an inherent component within teacher training and professional development, having previously been an additional course and often considered irrelevant to teaching practice. The current paper discusses the relationship between educational psychology and teacher preparation. Educational psychology's contribution to teachers' professional development is delineated through the constructs of teachers' prior beliefs about teaching, reflective practice and self-efficacy, while its contribution to the improvement of teacher-pupil interaction is viewed through the lenses of instruction theories, social and emotional learning, special educational needs and classroom management. It is argued that through a productive dialectic dialogue between educational psychology and education, educational psychology provides the knowledge defined by its field to be utilized by teachers, whereas at the same time, teachers gain a wider reconceptualization of their practice.