St George's Ascot has been awarded the highest level of 'excellent' in both areas of the educational quality inspection by the Independent Schools Inspectorate (ISI).
Head Liz Hewer said: "I am delighted that we were awarded the highest category of 'excellent' in both categories for Educational Quality.
"The report is a testament to our pupils of whom I am very proud, as well as the staff, parents, governors and alumnae, who all work together to make St George's Ascot the school I am privileged to lead.
"The values of community, kindness, hard work, support and integrity shine through in this report and it is an impressive reminder of all the excellent work we do in and outside of school."
The inspection report commented that pupils are '...highly confident, combining healthy self-knowledge, first-class social skills and an awareness of the world around them'.
The report also said that '...achievements in co-curricular activities are extensive; [they] achieve well across all areas of the curriculum and particularly in the creative subjects.'
St George's is celebrating its 100th anniversary this year.