Aaron Marks graduates this spring with a business degree from a good college, Carnegie Mellon University in Pittsburgh, and, unlike many of his classmates, a good job.

He also has $191,000 in student loan debt.

Mr. Marks’s debt is extraordinarily high, but stories like his abound. Two-thirds of students graduate with debt, to the tune of $25,000, on average.

Keeping interest rates low on federally subsidized student loans – a challenge that has lately occupied Washington – would make only a dent in what student borrowers owe. Hence, the conversation is beginning to shift to the other side of the equation: the rising cost of college.

Between 1999 and 2009, tuition at public four-year colleges rose 73 percent on average, and tuition at private nonprofit colleges jumped 34 percent. In the same period, median family income fell by about 7 percent.

‘One of the reasons we have a hard time wrapping our arms around [the college affordability issue] is that there’s not one villain or one hero,’ says Patrick Callan, president of the Higher Education Policy Institute, a nonpartisan organization focused on higher ed issues. ‘It’s kind of the perfect storm.’

Among the contributing factors: state budget cuts, which prompted many public colleges to raise tuition […]