The Collin County district attorney's office says 17-year-old Matin Azizi-Yarand of Plano had planned to release a "Message to America" explaining his reasons for the attack.
Authorities say he spent more than $1,400 buying weapons and tactical gear, and had been trying to recruit others to help him in the shooting planned for this month.
Azizi-Yarand is charged with criminal solicitation of capital murder and making a terroristic threat.
He is being held Wednesday at the Collin County jail on a $3 million bond. Online jail records don't indicate that he has an attorney.
He faces life in prison on the criminal solicitation charge alone.