Educational systems worldwide promote the use of collaborative networks to foster teacher learning and improve practice in the pursuit of educational change to address longstanding equity and achievement issues. New Zealand is no exception, with its Communities of Learning/Kahui Ako policy mandating collaboration spanning across schools--a mandate that has proven to be challenging. In this paper, we examine the case of one kahui ako where a social network analysis had revealed that, despite collaborative goal setting and the allocation of remunerated leadership positions, there was a paucity of ties across the five schools involved. Taking a theory of action approach, we uncover and describe the constraints that determine the lack of across-school interactions. We discover that trust issues, competition between schools, and behavioural norms requiring positive and non-evaluative interactions combined with goals that allow for but do not require collaboration, limit teachers in the network to essentially collaborating only with those they have an existing social relationship with. We conclude that although the achievement goals are worked on (by chance rather than design), they are not achieved and it is unlikely organisational learning will occur within the kahui ako. However, by describing the constraints dictating the patterns of interaction we also provide insight into a means of moving forward, and improving the collaboration patterns so that they might contribute to positive change in teaching and learning.