Background: The target group of this study concerns young people with a mild intellectual disability. The central research question is: What evidence can be found in the literature for common and specific factors for a play therapy intervention for young people with a mild intellectual disability struggling with aggression regulation. Method: The criteria used for selecting articles are presented according to the PRISMA, and the PRISMA guidelines for writing a review have been applied. Results: Common factors have been found in the literature that relate to the relationship between therapist and client and the therapeutic skills of the play therapist. Clues have also been found for specific factors of play therapy, such as the use of play as a language and a connection with the child's inner world. In addition, certain factors have been found that are specific to the target group of this article. The non-verbal element of play therapy is an active part of this.