The 14-year-old was last seen at about 6pm on September 9.
She is described as white with dark hair and was last seen wearing a grey jumper, black leggings and black trainers.
It is believed she may be in the Worthing area with friends.
Anyone who sees her or knows her whereabouts is asked to report it to Sussex Police online or call 101 and quote serial 1386 of 09/09.
