Guest editors: Bjørn Smestad, Monica Johannesen, and Hanne Christensen

What are the prevalent understandings of the concept of teachers' professional competence? What knowledge forms and learning arenas are significant in developing teacher competences for the 21^st century? In what ways can transdisciplinary goals of teacher education, such as diversity, R&D, and digital competence, contribute in forming teachers' professional competence? This special issue's contributions address a variety of perspectives on core concepts for understanding the complexity of teachers' professional competence.