Although modern mental health systems increasingly require evidence-based practice (EBP), clinicians continue to object to restrictions on their professional independence, which they may perceive as counterproductive, divisive and even demeaning. In the face of such deep-seated objections, do we really need to strive for an evidence-based approach to supervision? We believe so, and begin our argument by noting a colourful illustration of the problems that can exist in the absence of EBP, those of poor training, therapist drift and weak professional regulation. Next, we present EBP as a mechanism to reduce such unacceptable variability in the way that treatments are delivered. We then apply the lessons from this divisive situation to the practice of clinical supervision, outlining a rationale for an inclusive, synergistic way forward. A number of fundamental psychological motives for this integration are noted, including supervisor training that is informed by practice-based research, corrective feedback on supervision, and a supportive professional system. Illustrative examples are provided in each of these areas. It is concluded that the traditional gulf between research and practice can and should be bridged in relation to supervision.