This study explores how the reception teacher understands her responsibility to support newly arrived migrant pupils' mental well-being in her everyday practices. The three interconnected circle model represents mental well-being as a prerequisite for integration and for academic and social development. The teacher's self-perceived responsibility and self-guided initiatives reveal that a teacher can construct pedagogies that promote pupils' mental well-being if he or she is motivated and sees the need for it. Implications for policy and practices are discussed.