A girls school between Buckingham and Milton Keynes is set to open a Sixth Form in September next year.
Thornton College announced the news following a feasibility study which included discussions with both current and prospective parents.
The college says it has seen record numbers of new admissions over the last few years and that the proposal has had overwhelming support.
Jo Storey, the new head of Thornton College said: “The demand for the modern style of girls’ education that Thornton provides is extremely high.
“Parents are looking for a school which marries a first class academic education with a breadth of co-curricular opportunities, a warm and friendly environment and strong Christian values.
“Until now girls have only had this wonderful educational experience to age 16.
“We provide the very best educational experience for all and can now offer a first class preparation for university and life beyond.
“Thornton staff have a wealth of ‘A’ level teaching experience.
“We will also be recruiting appropriate staff for specific subjects where required and a Director of Sixth Form.”
In the first year the Sixth Form will be housed within the existing school building but within its own redesigned area.
This area will include a common room, additional classrooms and meeting rooms together with office space for staff.
As part of plans to open the new Sixth Form, a teaching programme to incorporate A Levels and vocational qualifications has been developed.
Detailed financial planning was also undertaken.
An information evening about the new Sixth Form is being held at the college on Thursday December 3 at 7pm.
The college is just off the A422 between Buckingham and Stony Stratford.