Background: The social climate of inpatient facilities is thought to be an important contributor to treatment outcome. However, little research has focused on this construct within secure forensic services for people with intellectual disabilities (ID). Therefore, the objective of this study was to investigate the social climate of two different types of secure units ("low" secure vs. "medium" secure) contained within the same facility for offenders with ID. Two hypotheses were generated: (1) residents would rate the social climate of the whole facility in a more negative direction than staff, and (2) residents and staff would rate the social climate of the "low" secure unit in a more positive direction than that of the "medium" secure unit. Method: Using a 2 (factor "Participant" = Staff or Resident) x 2 (factor "Unit" = "Low" or "Medium" Secure Unit) between-subjects design, 18 residents and 37 staff members were recruited and completed the Correctional Institutions Environment Scale (CIES), a measure of social climate. Results: Residents tended to rate the units in a more positive direction than staff on some sub-scales. Participants rated the "low" secure unit in a more positive direction than the medium secure unit on two sub-scales of the CIES. However, on selected sub-scales there were differences. The findings of this study suggest that the CIES may be a valid instrument for use within forensic services for people with ID, and further suggests that residents and staff have different perceptions of the shared social climate, which may have implications for service development.