In this study on 32 teachers' learning in an informal learning environment, we analyzed changes in conceptions and behavior regarding students' active and self-regulated learning (ASL), and relations with the teachers' learning activities. Few relations were found between observed changes in behavior and learning activities. Changes in conceptions appeared to correlate with the activities obtaining new ideas, experimenting with new methods, and reflecting on why certain teaching methods seem to be effective and others not. Only one teacher became more ASL-oriented in both behavior and conceptions. The apparent variation in teachers' informal learning should lead to differentiated support for teacher learning in the workplace.