The girls have been identified as 15-year-old Theresa Marie Lorenz and 14-year-old Gloria Joy Lorenz.
Theresa is described as being 5'3" and weighing approximately 160 lbs. She has brown hair, hazel eyes, braces, and a scar on her left knee.
Gloria is 5'6, 170 lbs, with brown hair, and hazel eyes. She was last seen wearing red glasses.
The teens hail from the Philadelphia area and are unfamiliar with Chester County.
Anyone with information on the whereabouts of the girls are urged to contact police at (484) 340-3241.