The past decade has seen a very significant cultural shift in how group programs are delivered in prisons and in probation and parole settings in New South Wales, Australia. The agency responsible for custodial and community corrections services, Corrective Services New South Wales (CSNSW) is making its way from a culture of considerable autonomy, where staff largely wrote and ran group programs in the way that seemed best to them, to an organisation where systems exist for accreditation, training, supervision and systematic data collection. The transformation to model agency is not complete, but considerable progress has been made and this is borne out by the preparation and publication of a number of significant papers describing the outcomes of program interventions. This paper appraises the progress so far in the introduction of evidence-based group work and offers some reflections on the challenges faced in moving a large organisation concerned with security and offender supervision towards best practice in group rehabilitative programs.