The purpose of this study was to investigate teaching within the framework of the philosophical social action theory developed by Professor Tuomela in order to argue for the claim that teaching is a social concept. The outcome is likely to have important implications for the development of theories about factual and conceptual phenomena within pedagogy. The joint action of teaching performed by the teacher and pupil was analyzed in the purposive-causal theory. The most important means of analysis was the action language and the concepts connected with it: intentionality and we-intentions. The particular theses argued for were: (1) the concept of teaching requires the concept of learning as an action, not as a learning outcome; (2) the concept of we-intention is needed to account for the joint action of the teacher and the pupil. Part of the analysis involved going through the conceptions of teaching in the educational literature and clarifying misconceptions. In particular, teaching was viewed in terms of the collective acting jointly and in terms of modes of teaching. In institutionalized teaching, the jointness of the teaching action prevails between the teacher and each pupil separately, that is, the pupils' component actions are not dependent on each other's actions. As for the we-intention, additional conditions can be set for the concept in the case of instruction and indoctrination. (Author)