Purpose: The focus in professional learning is often on formal activities such as workshops, conferences and courses. There is also a tendency to focus on formal programmes of coaching and mentoring in teacher education. Emphasising the formal activities means that everyday informal learning in educational settings is overlooked. Informal coaching and mentoring could be utilised to support teachers' career-long professional learning. Design/methodology/approach: This is a conceptual paper which draws on the author's research and seeks to expand what is considered as professional learning within teacher education -- namely, informal coaching and mentoring. To understand how to support this professional learning, the lens of social practice is used with an emphasis on learning environments and learning practices. Findings: Coaching and mentoring can be identified in informal encounters in the staffroom, school corridors and many places and situations. Findings are presented in relation to the importance of informal learning from and with colleagues and the role of headteachers. Originality/value: More attention has been paid to informal learning, but there is still a need for what could be termed an "informal turn". Understanding that informal coaching and mentoring afford professional learning opportunities to the teachers who both provide and receive coaching and mentoring can help to support their learning. Recommendations are provided on how educational settings can facilitate and support these professional learning opportunities while preserving their informality.