Introduction: Features of intellectual disability (ID) and/or autism spectrum disorder (ASD) may hinder responsiveness to interventions typically used during psychiatric hospitalization to manage severely disruptive behavior, and could increase the likelihood of experiencing restraint and/or seclusion (R/S). This study investigated the occurrence of R/S in psychiatrically hospitalized children rated by their treatment team as having ID and/or ASD and those who were rated as having neither. Methods: Pre-adolescents (N = 777; M = 9.71; SD = 2.71; Range 5-12) consecutively admitted to an acute psychiatric hospital during a one-year period were assigned a consensus DSM-5 diagnosis of ID (n = 295), ASD (n = 48), Both (n = 77), or Neither (n = 361). R/S occurrences were recorded in terms of their frequency and duration. Results: 52% of patients experienced at least one R/S while hospitalized. The modal number of R/S events for this sample was 0, and for children who experienced any R/S, the mode was 2. Comparisons (ID, ASD, Both, Neither) showed statistically significant differences (p <0.001) in R/S events. Children rated as meeting diagnostic criteria for ID (68%; M = 13.9), or Both ID and ASD (78%; M = 18.2), had elevated rates of R/S events compared to cases with Neither diagnosis (35%; M = 7.3). ASD alone (50%; M = 10.0) was not associated with an increase in R/S compared to cases with Neither diagnosis. Data on the duration of these events completely paralleled the frequency results. Conclusion: Children who met DSM-5 criteria for ID had a greater risk of experiencing R/S during psychiatric hospitalization. To reduce the occurrence of R/S, interventions must be refined and staff specially trained to address the complexities of treating children with ID.