Background: Little is known about the social ecology of residential schools. This study examined staff/student interaction and student activity in a traditional residential unit and an "independent living unit" (ILU) in a school for students with intellectual disabilities and challenging behaviour. Method: Staff and student behaviours were observed for 23 students aged 8-16 years, five from the ILU and 18 from the traditional unit. Results: Students received staff assistance to complete activity for under 6% and 1% of time, and were constructively engaged for under 50% and 20% of time, in the traditional unit and ILU respectively. Few differences were found between the units. Conclusions: Despite higher staffing ratios, levels of staff assistance and attention and resident activity in the school resemble mean levels in comparable adult community services. Further research into outcomes in residential schools seems warranted.