St Mary's JuniorSchool is a Voluntary Aided Roman Catholic Junior School for girls and boys between the ages of 7 and 11 years. The school lies within the Archdiocese of Southwark and in the pastoral area of South West London.
The school lies within the parish of The Holy Cross Carshalton, and also serves the parishes of Our Lady of the Rosary in Sutton, The Holy Family in Sutton, and St Margaret's in Carshalton Beeches.
Iti 1890 a Catholic school was opened in Sutton where it was attached to the Church of Our Lady of the Rosary. Four years later, the numbers of pupils having increased, new accommodation was provided in the grounds of Carshalton House in Shorts Road. The School thrived in these premises until 1966 when the infants were separated from the juniors and the infants' school was established on its present site in West Street. The junior school remained in the Shorts Road premises until 1980 when the school moved to its present modem location, which was originally St Philomena's prep school.