Rebecca was last seen in Gillingham on November 25, 2002 after being dropped off near the railway station by her grandparents.
Despite extensive investigations by police, several false sightings and family appeals, Rebecca has not been seen.
Rebecca used to go to the former Chapter School, in Strood, she was close to her family and had a passion for horses.
She had been staying at Beatty Avenue with friends. Her mum, Lynne Simmonds still lives in the family home in Bingham Road, Frindsbury, near Strood.
Rebecca was 5ft 8in, slim and had mousy brown, curly hair at the time she went missing.
If you have any information on Rebecca’s disappearance or her current whereabouts, please contact police on 101.
Alternatively, contact the independent charity Crimestoppers anonymously on 0800 555 111, or text the charity Missing People on 116 000.