Private student loans, for example, usually charge higher interest rates and are harder to discharge in bankruptcy.

In addition, many lenders lowered their underwriting standards so that they could originate and then sell off more loans, even if the loans were based on terms the borrowers could not possibly fulfill. Defaults became even more inevitable after the recession slashed graduates’ job possibilities.

“Subprime-style lending went to college and now students are paying the price,” the education secretary, Arne Duncan, said. “We still have some work to do to ensure that students who take out private student loans have the same kinds of protections offered by federal loans. In the meantime, if you have to take out a loan to pay for college, federal student aid should be your first option.”

In a conference call with reporters on Thursday, Mr. Duncan and Richard Cordray, the director of the Consumer Financial Protection Bureau, described ways in which private lenders might have misled borrowers or failed to be entirely transparent about their borrowing terms.

The government officials said they are not currently pursuing action against lenders for these past lending practices, but are monitoring the market now under authority granted by the Dodd-Frank financial regulation legislation. They have also urged Congress to reconsider the treatment of private loans in bankruptcies and to require more disclosure in the loan application process.