Teachers with strong professional agency (TPA) in the classroom make efforts to constantly learn and develop their teaching practices. The aim of the present study is to identify teachers' different TPA development profiles and their association with experiencing burnout symptoms and abilities to use proactive strategies in regulating well-being. A total of 1920 Finnish primary school teachers responded during the two-year follow-up study. The data were analysed using longitudinal latent profile analysis. Four profiles were found: (1) High and stable professional agency; (2) Moderately high professional agency; (3) Increasing professional agency; and (4) Decreasing professional agency. Most teachers experienced strong and stable professional agency and only few changes in their sense of professional agency over time. Socio-contextual burnout symptoms and proactive strategy use differentiated the profiles well. Teachers with lower professional agency profiles experienced more burnout symptoms and less ability to use proactive strategies.