Professional teacher communities appear to be positively related to student learning, teacher learning, teacher practice and school culture. Teacher collaboration is a significant element of these communities. In initial teacher training as well as in-service training and other initiatives for teacher learning, collaborative skills should be addressed in, for example, collaborative learning tasks, supported with technology. In this study, eight learning tasks of three initial teacher training programmes were investigated concerning the collaboration of 41 student teachers. Various task elements (structure, learning goal and content) affected the participation of student teachers in the tasks, their interaction, and the nature of their communication. The results indicate that reflection-oriented tasks stimulated participation, and in combination with task structure also interaction. Structured tasks which required critical reflection on personal experiences and perspectives triggered task-related communication and a deep level of information exchange. (Contains 2 tables and 3 figures.)