Purpose: The aim of this paper is to investigate the feasibility of using the core conflictual relationship theme (CCRT) method, used to assess relationship patterns and interpersonal schemas, within a small group of men who had intellectual and developmental disabilities (IDD). The relationship anecdote paradigm interview, with minor adaptation, was used to collect material from participants necessary to generate a CCRT. CCRTs formulated in the study are described and consideration is given to the potential clinical application of CCRT method in this patient group. Design/methodology/approach: A small sample of four men with IDD was taken from a medium-low secure forensic service. Initial interviews, necessary to elicit narrative anecdotes for CCRT formulation, were conducted at the start of a psychotherapeutic treatment study. Trained judges completed a CCRT formulation for each participant. Findings: Participants in the study were able to provide personal information necessary to formulate a CCRT. Unexpected common themes were shared in participants who had committed contact sexual offences, this differed from a participant with autistic spectrum disorder who had committed a non-contact sexual offence. The CCRT method can be feasibly used in a mild IDD population. The CCRT method is clinically relevant and provides an opportunity for the exploration of clinical micro-theories related to interpersonal schemas found in offenders who have IDD. Originality/value: This is the first study, to our knowledge, reporting results of the CCRT method with adults who have mild intellectual disabilities. (PsycINFO Database Record (c) 2017 APA, all rights reserved)