In this study the relationship between teacher learning and collaboration in innovative teams was explored. A comparative case study was conducted in five temporary teams in secondary schools. Several quantitative and qualitative data collection methods were used to examine collaboration, teacher learning, and the context for learning and collaboration. In cross-site analysis two complementary patterns of teacher learning and collaboration were identified. Collaboration in all teams could be characterized as "sharing". However, sharing was further specified with regard to differences in the content and aims of sharing. Different types of sharing were related to teacher learning. The results give cause to rethink the nature of interdependence in collaboration, and the nature of the relationship between collaboration and learning. A practical result may be that collaboration in innovative, temporary, and voluntary teams could be a promising direction for teacher professional development. (Contains 3 tables and 1 figure.)