Longview police said that Charity Johnson was arrested after telling officers she was "Charite Stevens".
She was being held in Gregg County Jail on 500 dollar (£300) bond for allegedly giving false information to police.
Police had been called to a flat when the person Johnson was staying with said she no longer wanted her living there. Police gave her a trespass warning.
The principal at a small private school in East Texas says Johnson enrolled in October with a guardian and filled out paperwork indicating she was 15.
Police say she is 34, although jail records list her as 31.