The term positive behaviour support (PBS) is used to describe the integration of the contemporary ideology of disability service provision with the clinical framework of applied behaviour analysis (ABA). Assent, the participation consent of those not legally able to consent, has gained recent popularity in the fields of ABA and PBS. The goal of assent-based ABA and PBS is a person-centered approach to assessment, intervention, and all other decision-making. In this model, the learner's assent withdrawal for participation is honored, whether it be a vocal 'no' or a non-vocal expression of verbal behaviour. There is currently a limited subset of studies that mention or utilize assent with learners in ABA or PBS. The lack of published research can make assent-based practices seem to be a choice of the practitioner. The authors of this manuscript seek to further define assent, illuminate the necessity of assent-based practices, and offer assent-based procedures in ABA- and PBS-based intervention.