Allison Benitez, 19, and her mother, Marie Benitez, 53, were last seen July 14 in the city of Perpignan in southern France, The Local.fr reported Thursday.
Allison is due to participate in the Miss Roussillon competition on Sunday and her friends are concerned about where she might be.
"Allison had no reason to leave, to run away," a friend told a Paris newspaper. Competing in the Sunday pageant "was her personal ambition this summer."
Cindy Filipiak, organizer of the Miss Roussillon contest, described the teenager as "the most motivated of candidates."
Allison's father began searching for her July 15 after she failed to attend a pageant rehearsal.
Police called the disappearance "worrying."
The women left behind their car and a pet dog. They have not answered their phones, used their bank accounts or posted to Facebook or Twitter.