Ensuring therapeutic competence in the delivery of third-wave therapies is important in supporting translation of research into clinical practice, maintaining the integrity of the therapy, keeping clients safer, and potentially enhancing therapeutic effectiveness. First, the importance of therapeutic competence is outlined. Second, a tool designed to assess the competence of mindfulness-based programme teachers is described in detail (the Mindfulness-Based Interventions: Teacher Assessment Criteria (MBI:TAC: Crane et al., 2021), along with its use, impact, how to train as an assessor, and continued evolution. A formative reflective tool, based on the MBI:TAC, the Mindfulness-Based Interventions: Teaching and Learning Companion (the TLC; Griffith et al., 2021a) is then outlined. Third, approaches to training and therapeutic competence in various third-wave therapies will be briefly described.