Then the school will take girls and boys from the age of two up to 18.
Principal Jenny Palmer said they were delighted to make the announcement.
‘We are excited to be able to offer families with both girls and boys our unique Elizabeth College education,’ she said.
‘Our aspiration is that everything that parents and pupils currently enjoy about Elizabeth College – the outstanding teaching, excellent pastoral care, focus on individuals and superb co-curricular opportunities – will continue and indeed be enhanced by a fully co-educational environment.’
Parents were told about the decision yesterday, pupils are learning about it this morning.
The board of directors have decided to make the move to co-education in recognition of the needs of contemporary society, as well as build on the junior school’s co-educational offering.
‘We have seen first-hand the benefits of co-education with clear social, cultural and academic advantages stemming from girls and boys working together in and outside the classroom,’ a spokesman said.
‘We will offer the opportunities of an education at Elizabeth College to girls and provide a route through to secondary education for all our junior school pupils, as well as welcoming girls from all of the island’s primary schools.
Girls will be able to join Year 7 and Year 12 in September 2021, with a view that the school will be entirely co-educational by 2025.
The junior school has been co-educational since 2008.
Board chairman, the Dean of Guernsey, the Very Rev. Tim Barker, said: ‘We have seen that parents are increasingly looking for a school which can serve both their daughters and sons, from the preschool all the way through to sixth form.
‘This change continues the traditions of Elizabeth College in serving the whole of the Guernsey community and means that brothers and sisters will be able to enjoy together the excellent, broad and stimulating education on offer here.’
Elizabeth College was founded in 1563 under the orders of Queen Elizabeth I with the aim of training priests who would preach in island parish churches according to the principles of the Reformation.
The upper school has around 520 pupils, the junior school 280 and pre-school 70 pupils.The junior school and pre-school are already co-educational.
Since 1999 there has been a sixth form partnership between the college and The Ladies’ College.