"Like many middle-class families, Cortney Munna and her mother began the college selection process with a grim determination. They would do whatever they could to get Cortney into the best possible college, and they maintained a blind faith that the investment would be worth it. Today, however, Ms. Munna, a 26-year-old graduate of New York University, has nearly $100,000 in student loan debt from her four years in college, and affording the full monthly payments would be a struggle. For much of the time since her 2005 graduation, she’s been enrolled in night school, which allows her to defer loan...