Kingston Grammar School is an independent co-educational day school in Kingston upon Thames, England. The school was founded by royal charter in 1561 but can trace its roots back to at least the 13th century. It is a registered charity under English law. It was a boys' school from its foundation until 1978, when the first girls were admitted.
 In 2018 the GCSE results recorded 85% of grades were A*/A or 9–7, and at A-level 62.7% of all grades were A or A*. In 2008 the Good Schools Guide described the school as "An academic school with a modern edge".
 The school's history is traceable into the Middle Ages, where there are references to schoolmasters like Gilbert de Southwell in 1272, described as "Rector of the Schools in Kingston", and to Hugh de Kyngeston in 1364 "who presides over the Public School there". Notable in the school's history are the founding and endowing of the Lovekyn Chapel by John and then Edward Lovekyn in 1309-1352 and later by William Walworth in 1371. The chapel is still used by the school.
 After the dissolution of the chantries in 1547, the chapel fell to the Crown and was deconsecrated. It, and by now its substantial related endowments, fell to a court favourite, Richard Taverner. He preserved the chapel so when in 1561 the bailiffs of Kingston petitioned Queen Elizabeth I for a royal grammar school, the building was still usable. The Queen granted the school a royal charter in 1561.
 The school became a direct grant grammar school in 1946 as a result of the Education Act 1944 and became independent in 1978 after the scheme was abolished by the 1974–79 Labour Government. In the same year, the first girls were admitted.
 KGS celebrated the four hundredth anniversary of its founding charter in 1961 with a visit from Queen Elizabeth II. In 2005 she opened the new Queen Elizabeth II Building, where she unveiled a plaque, met with students of Music and Geography and watched an excerpt of the play "Smike" after which the new Recording Studio was named.
 On 1 May 1965 the school opened its new playing fields at Thames Ditton, alongside which was built its boathouse, donated by R.C Sherriff. Prior to this it had shared Kingston Rowing Club's boathouse, and had owned much smaller playing fields at Ditton Road, Kingston.
 There are five houses, named after Medieval and Elizabethan figures connected with the school and the city of London, with the exception of Stanley Shoveller, an Old Kingstonian who played international hockey in the early 20th century.
 
 The school has a sporting programme, with the main sports being football, netball, tennis, hockey, rowing and cricket.
 Hockey, rowing and cricket are the school's performance sports with hockey and rowing having  achieved successes at national level, including three national hockey titles in 2019.[citation needed]
 The 'R.C. Sherriff' rowing boathouse is on the Thames at Thames Ditton, Surrey. Students may take up rowing beginning in Third Form (Year 9) and participate in local and national regattas, including The National Schools Regatta and Henley Royal Regatta.
 The school has produced professional and international athletes, most commonly in hockey and rowing but also more recently in football and cricket.