There is strong evidence of the prevalence of trauma among people admitted to forensic services. Consequently, forensic services are adopting trauma-informed philosophies of care and treatment. However, there are currently no scales available to measure the extent to which people admitted to forensic services experience them as trauma-informed. This thesis aimed to develop and validate such a scale using an exploratory sequential design. The qualitative phase of the research utilised focus groups to explore the meaning of trauma-informed care from 10 service users’ perspectives. Data from the focus groups guided the development of the TICSCale. The TICSCale was administered to 80 service users in 10 forensic services across England. Principle components analysis revealed a unidimensional structure. Further research is required to strengthen the psychometric properties of the TICSCale. However, it offers a promising first step toward developing a robust measure of TIC supportive climates in forensic services.