School Inspection Service is an independent body established to carry out school inspections under Section 162A of the Education Act 2002. It services registered, independent schools and comes jointly under the control of Ofsted, and the Department for Children, Schools, and Families (DCSF).

SIS was approved by the Secretary of State in 2006 and is staffed by a Co-ordinating Inspector, approved by the DCSF and a team of inspectors most of whom are ex HMIs (Her Majesty's Inspectors) and all of whom are approved for their operations in SIS by DCSF. Included within the team are a number of HMIs who have specialised in particular educational disciplines such as special needs, post 16 education, primary class specialists, school management, and other specific areas.

SIS retains the services of an independent Complaints Adjudicator of considerable experience. This person exists to determine any complaints raised by aggrieved parents, teachers, or other involved personnel, when the earlier elements of the complaints procedure have been exhausted. The Complaints Adjudicator is not related or connected in any way with SIS or its staff and stands alone to provide a totally independent, unbiased, and non-prejudicial judgement.

Ofsted, the Government's official inspection body, monitors a certain proportion of the SIS inspections every year to ensure that they are carried out with sufficient rigour and according to Ofsted's laid-down parameters of inspection and reporting.