The Department of Education oversees various programs to help students pay for the costs of postsecondary education. This Congressional Budget Office (CBO) study focuses on the two largest student loan programs created under the authority of the Higher Education Act of 1965 (as amended): (1) The Federal Family Education Loan (FFEL) program, which dates back to the mid-1960s, guarantees student loans made by private-sector lenders; and (2) The William D. Ford Federal Direct Loan Program (FDLP), which began operating in 1994, makes loans directly to students or their parents. This study--prepared at the request of the Ranking Member of the Senate Budget Committee--compares the budgetary and fair-value costs of the federal student loan programs. It also looks at several options for modifying those programs, including eliminating the guaranteed loan program after July 1, 2010, and expanding direct lending. "Assumptions and Analysis Underlying CBO's Fair-Value Subsidy Estimates" is appended. (Contains 4 tables, 1 box, and 54 footnotes.)