This study consists of five international articles and an introductory background review. Its focus is on the nature and structure of teachers' pedagogical knowing. Pedagogical knowing is characterized as an active process by which teachers perform their duties in situations involving intense social interactions. This study treats teachers' pedagogical knowing as a broad theoretical concept and as an extended practice. Patterns of teachers' narratives are analysed as reflecting the general nature of this type of knowing. The theoretical background consists of three concepts. The idea of phronesis argues that teaching can be understood as an embodied judgement linking knowledge and virtue. The concept of relational knowing draws attention towards that which lies ahead of a teacher in a given situation. The pervasiveness of pedagogical knowing explores that situation more in depth. Together, the concepts extend the theoretical bases of the individual articles. Based on a broad concept of teachers' pedagogical knowing, analyses of qualitative data are presented. Narrative interviews provide data for descriptions of teachers' justifications and their individual epistemologies. In comparative cross-case studies intersubjectivity is brought to the fore. The article studies investigate how teachers' knowing is related to others. An individual case study presents the complex practice of teachers' pedagogical knowing. In concert, three types of narrative analyses are used to explain the nature and structure of teachers pedagogical knowing. Against the background of these analyses, five characteristics of this type of knowing are portrayed. The results show that the concept and practice of teachers' pedagogical knowing contains certain fundamental tensions inherent in teaching. Five stand out: care and respect for students, the compelling power of teachers' personal justifications, the absence of a shared code of practice, the struggles to balance teachers' public and private roles, and the basic uncertainty within the teaching profession. To fully grasp the diverse nature of pedagogical knowing, its general social and cultural context should be taken into account. The general context is particularly significant in the ethical issues manifested in teachers' work.