There are many challenges in incorporating an evidence-based approach into clinical practice and a large literature exists on various barriers and facilitators. Within this context, we have developed a framework to advocate an empirical approach to therapeutic interventions, using our Model to Assess Treatment Effect (MATE). The MATE is designed to characterise how an intervention is delivered to an individual patient/client. It is organised hierarchically into seven levels, from low levels of capacity to demonstrate treatment effect (e.g., Level 1: treatment commenced without pre-intervention assessment) to high levels where cause–effect relationships can be established between the intervention and the behaviour being treated (e.g., Level 6: implementation of a well-designed single-case experimental design). Consequently, the MATE captures all levels of clinical intervention and can be applied readily to an individual patient, as well as an entire clinical setting. In this paper, we present a decision tree in the form of a detailed flow-chart which assists the clinician to classify treatment delivery on the MATE. We believe that the MATE has the capacity not only to document current clinical practice, but also to provide a model whereby future treatments can be planned and implemented with greater scientific rigour and hence accountability in relation to treatment outcomes.