34 CFR §685.101

1. (a)Colleges, universities, graduate and professional schools, vocational schools, and proprietary schools may participate in the Direct Loan Program. Participation in the Direct Loan Program enables an eligible student or parent to obtain a loan to pay for the student's cost of attendance at the school.
2. (b)
   1. (1)An eligible undergraduate student who is enrolled at a school participating in the Direct Loan Program may borrow under the Direct Subsidized Loan and Direct Unsubsidized Loan programs.
   2. (2)An eligible graduate or professional student enrolled at a school participating in the Direct Loan Program may borrow under the Direct Subsidized Loan, Direct Unsubsidized Loan, and Direct PLUS Loan programs, except that a graduate or professional student may not borrow under the Direct Subsidized Loan Program for any period of enrollment beginning on or after July 1, 2012.
   3. (3)An eligible parent of an eligible dependent student enrolled at a school participating in the Direct Loan Program may borrow under the Direct PLUS Loan Program.