The Education Secretary Justine Greening has responded to pressure from cross-party MPs by agreeing to make sex and relationship lessons mandatory in all schools.
The reforms would force all secondary schools to provide pupils with "age-appropriate" sex and relationship education (SRE), while primary schools will be obliged only to teach pupils about relationships.
The decision follows years of campaigning by MPs and health and education experts, including Shadow Equalities Secretary Sarah Champion and the Conservative chairman of the Health Select Committee Sarah Wollaston.
Announcing the measures today, Ms Greening acknowledged current SRE guidance is becoming "increasingly outdated" and pledged to ensure "every child has access to age appropriate provision".
"The statutory guidance for Sex and Relationships Education was introduced in 2000 and is becoming increasingly outdated," she said.
"It fails to address risks to children that have grown in prevalence over the last 17 years, including cyber bullying, ‘sexting’ and staying safe online.
"I am today announcing my intention to put Relationships and Sex Education on a statutory footing, so every child has access to age appropriate provision, in a consistent way.
"The Department for Education will lead a comprehensive programme of engagement to set out age-appropriate subject content and identify the support schools need to deliver high-quality teaching."
In her statement, the Secretary of State stressed that parents will continue to have a right to withdraw their children from sex education lessons.
She added that schools will have "flexibility" over how they teach these subjects, and that faith schools will continue to be able to teach "in accordance with the tenets of their faith".
Ms Greening also set out her intention to make PHSE lessons (Personal, Social and Health Education) mandatory in academies and maintained schools.
The changes are being introduced through amendments to the Government's Children and Social Work Bill which is currently going through the Commons.