This paper offers a commentary on the debate between Marshall and Mann on the desirability and merits of treatment manuals in the treatment of sexual offenders. Marshall offers a view of manuals as restrictive to clinical practice and as stifling to clinical innovation. Mann takes the position that manuals are a vital component in effective correctional practice. The commentary suggests that these contrary views are understandable: Marshall takes a clinical perspective and advocates best practice; Mann speaks from a realist forensic perspective in which manuals offer a practical means to deliver treatment on a large scale within prisons and probation. Of course, both positions have their merits and it is suggested that the two are perhaps not irreconcilable if the skills of the practitioner and model of treatment delivery are taken into account.