WhatsApp is raising its minimum age from 13 to 16 across Europe.
It will ask people to confirm how old they are when new terms are rolled out in the coming weeks.
It's unclear how this will be checked, while the minimum age will remain 13 outside Europe.
In countries where young users do not have the 'authority' to sign up, WhatsApp says a parent or guardian must agree to their terms on the teenager's behalf.
Social media expert Toby Beresford says not all parents will be pleased.
He observed: "If you're a family and you've been used to using WhatsApp as a way of keeping the family conversation going... then you might need to look for a different supplier."
It comes as technology companies work to update their terms before the EU's General Data Protection Regulation (GDPR) rules come into effect next month.
