This article describes the results of the first phase of a research project to develop, implement, evaluate, and improve arts therapies interventions for young offenders in secure care. By means of a naturalistic/constructivistic research methodology in combination with grounded therapy methodology, practice-based evidence has been generated. Core problems of young offenders that are connected to delinquency have been described and arts therapies interventions have been developed that can be used to change these core problems. Core problems are problems with self-image, with expressing and discharging emotions, the inability to resolve interpersonal problems and finally, negative cognitions. In co-creation with practitioners, interventions have been developed for drama therapy, music therapy, art therapy and dance-movement therapy. A treatment theory has been developed that explains the working of arts therapies by means of the first author's theory of analogy. This theory explains arts therapies by means of the equality between forms of expression in art and the core self consciousness as described by Damasio and the vitality affects within the core self as described by Stern.
