The 55-page booklet, produced by the National Children's Bureau and the Sex Education Forum, addresses concerns that private-school teachers do not get enough training in personal health education.
It offers practical advice on developing a sex education curriculum. It also provides guidance on the role of the teacher and the school nurse.
Gill Frances, director of the NCB, said: "The desire to achieve good exam results may overshadow other areas. But the pressures to have sex are exactly the same, wherever boys and girls are."
Pauline Davies, president of the Girls' School Association, said the guide would be viewed with interest but added: "The GSA already organises a programme of in-service training that deals with sex-education issues."
"Sex and relationships education: a guide for independent schools and those working with them" will be distributed to all independent schools in England