Interprofessional practice between speech and language therapists and teachers involve sharing knowledge and experiences to achieve a common goal of improving child outcomes. Although interprofessional practice has widespread support from both disciplines, it is not always easily implemented in day-to-day practice and numerous challenges have been documented. This study attempts to address these challenges through an epistemological perspective of interprofessional practice between teachers and speech and language therapists. Action research methodology was employed for this inquiry that spanned the duration of a school year. Data analysis placed an explicit focus on the experiences of interprofessional practice between the speech and language therapist and teachers, including an examination of how action was agreed and the processes underpinning collaborative working. An epistemological lens facilitated a more in-depth consideration of the diverse ways of knowing implicit in interprofessional practice and provided guidance on how to overcome the barriers, and realise the potential, of collaboration between speech and language therapists and teachers in daily practice. Four factors, rooted in an epistemological perspective, were generated from the analyses as core tenets of effective interprofessional practice. These included securing a participatory space; actively facilitating power-sharing; balancing the status of practical knowing with propositional knowing and anchoring interprofessional practice in collaboratively designed, practical activities that integrate ways of knowing. The former four factors, and their implications, offer concrete and practical direction for practitioners and educators on how to achieve effective interprofessional practice to help improve child outcomes collaboratively.