Derbyshire Police concerned for the safety of Lisa Eastwood, 16, who was last seen in the Whaley Bridge area of the High Peak at around 1.20pm on Tuesday (October 16).
Lisa, who speaks with a strong Irish accent, is described as white, 5ft 10ins tall and of medium build. She has long, dark-brown hair and brown eyes.
Lisa may be wearing a dark-green jacket and blue skinny jeans.
It is believed she has links to the Essex area.
A police spokesman said: "Anyone who has seen Lisa, or has any information about her whereabouts is asked to contact us using one of the following methods.
"Please quote the reference number 687 of October 16 in any correspondence:
"Facebook – send us a private message to /DerbyshireConstabulary
"Twitter – direct message our contact centre on @DerPolContact
"Website – complete the online contact form www.derbyshire.police.uk/Contact-Us.
"Phone – call us on 101.
"You can also call Crimestoppers anonymously on 0800 555 111.
"Please note in the event of an emergency you should always call 999."