This article describes how school social workers and teachers perceive their cooperation with each other with regard to pupils' well-being in Swedish schools. A total of 23 qualitative interviews were conducted with a strategic sample of teachers and school social workers. The analysis of the interview data was based on Andrew Abbott's theory of the system of professions, and the cooperation and boundary work of the two professional groups are discussed in terms of jurisdictional conflicts and "cultural machinery". The analysis shows that on a general level both school social workers and teachers seem to agree about the need for school social work, but tensions and diverging views were uncovered when investigating the cultural machinery in their daily work. This study shows how both of these professional groups protect the boundaries of their own jurisdictions, but also how these boundaries are relaxed when social workers and teachers jointly try to solve everyday problems.