Elien Neimeijer

46 participate. Of the participants, 48% had a mild intellectual disability (MID; IQ 50-69), and 52% had borderline intellectual functioning (BIF; IQ 70-85). The mean total IQ was 69.7 (SD = 9.7). IQ-scores were based on diagnostic testing results and retrieved from the files of the participants. Participants had severe problem behaviour in combination with mental health problems and/or serious problems in all areas of life, often with a his- tory of substance use. Most participants were admitted because of externalizing behav- iour problems (i.e., aggression or a sexual offense) and/or internalizing problems (such as self-injurious behaviour and suicide attempt) (Delforterie, Hesper, & Didden, 2020). Participants were placed in the facility under criminal law (40%), civil law (23%) or were voluntarily admitted (37%). All participants need intensive care in a secure setting due to severe behavioural and mental health problems, similar to participants placed under criminal law in terms of required intensity of treatment and level of security. Treatment duration in both cases is rarely shorter than two years and can last ten years or more, depending on the participants’ legal status and risk of (re)offending. In this sample (N=248), mean treatment duration at the moment of data collection was two years and two months. Based on the psychopathology of the participants and the phase of the treatment (i.e., observation, treatment, and rehabilitation), treatment programs (e.g. aggression, addiction, or sexual offending behaviour), the security lev- els and care intensity vary between the units. While in some units the support is more distant, in other units the participants receive one to one guidance throughout the day. In this sample 5% of the participants resided in a high intensive care unit, 18% medium to high care unit, 24% on a medium care unit, 25% on a low to medium care unit and 28% on a low care intensity unit. Depending on the risk of (re)offending, legal status and treatment phase, residents move to living groups with different levels of restrictions and levels of security. In this sample 66% of the participants resided in a low secure living group, 16% resided in a medium secure living group, and 18% resided in a high secure living group. Procedure Data were collected in the context of routine monitoring of the ward’s climate within the facility . Each year, participants who resided in the facility were individually interviewed and completed the GCI. For the purpose of exploring associations between group cli- mate, aggressive incidents, and coercive measures, only data from one wave were used