Facebook is allowing users under 18 to post publicly on the site for the first time.
The social network said the move, which will allow teenagers to share updates with all users, was in response to demands for the service.
Until now users aged 13 to 17 were only able to share posts with "friends of friends" on the site.
A change will also mean teenage users will be given a default setting of "friends" only.
The move brings Facebook in line with other social networks such as Twitter which allows users to post publicly by default.
"One of the requests we hear direct from teenagers most often is the ability to share things in a public way, just as they can on other services," said Simon Milner, director of policy for Facebook in the UK.
"Teens are among the savviest people using social media... and they want to be heard."
In response to concerns the change would leave teenagers vulnerable to abuse, Facebook said it took their safety "very seriously."
Users choosing the public option will be reminded that their post will be visible to anyone.
Teens will be able to turn on Facebook's "follow" function so their posts will be seen in people's news feeds.
Teens are among the savviest people using social media... and they want to be heard
The social network said the changes were designed to "improve the experience" for teenagers on Facebook.
"They're expert at controlling who can see what they say and do on Facebook," said Milner.
"We therefore needed to give young people the chance to use Facebook in new ways."
New users are asked to give their date of birth when signing up for Facebook to prove they are over 13.
But the company does not verify the information allowing people to lie about their age.