The study that provides the context for this article developed from a major overhaul of the practicum in an undergraduate initial teacher education degree in which practicum roles and relationships were re-envisaged. The aim was to reinvigorate university-school practicum relationships through the collaborative development of a practicum where teacher professional knowledge and university scholarly knowledge could come together in the service of student teacher learning. The article reports a qualitative study involving 72 participants from one university and four primary schools. Analysed through the lens of "third space" the findings indicated that relationship and role transformations undertaken by the participants, along with collaborative practice during the practicum, were key to reinvigorating the practicum. In the discussion, we examine the main factors that contributed to the development of a "third space" between the university and participating practicum schools, and also note some cautions related to this development.