Multiple intervention approaches have been developed and implemented in criminal justice settings around the world, to support substance-involved offenders to reduce, or possibly eliminate, their problematic use of alcohol and other substances. To varying degrees, these approaches are founded on theory and supporting empirical evidence; in other instances, foundational theory and evidence appear to be lacking and, at times, this absence is total, with these latter approaches appearing to be based more on practitioner beliefs than published evidence. Similarly, the available research evidence indicates that even evidence-based treatment programmes can vary in terms of clinical effectiveness. The published literature demonstrates that the quality of the research underpinning this evidence can also vary, including the quality of research designs, choice of outcome indicators of programme impact, and length of follow-up.