The induction stage of teacher education in Ireland is currently at a major turning point. In 2013, the Teaching Council embarked on piloting a new form of induction and probation of teachers known as Droichead (Teaching Council, 2013a); this involved practising, experienced teachers mentoring and supporting newly qualified teachers (NQTs) during induction. It also involved mentors and principal teachers in the assessment of NQT progress; the assessment role was traditionally the remit of the Inspectorate as probationary work with NQTs. For various reasons, this departure has been met with opposition from within the profession and from teacher unions. A central focus of my research is an exploration of co-teaching as a pedagogy, as used by mentors and NQTs during the induction process. This research was conducted in a range of schools: DEIS, urban, rural, Droichead pilot schools, and special schools. Collaborative action research (CAR) engaged the participants in co-teaching lessons and professional development meetings. Collaborative practices were developed and fostered in schools and across school settings in communities of practice, which affected participants’ professional learning. The findings suggest that tensions, which NQTs and mentors face whilst establishing a professional relationship, were dealt with during reflections on practice and participation in co-teaching. Sharing of professional responsibility and collaboration, whilst still fostering the needs of teacher education at induction level, also added to the continuing professional learning of mentors. These areas are represented in the model for the development of professional learning and professional relationships through coteaching with CAR, which was designed in this study. The model developed here created a space where professional learning was developed in conjunction with professional relationships. This model moved away from the traditional models of induction and, instead, embraced innovation in teacher education in an Irish context.