May 1 is fast approaching, and with it the deadline for high-school seniors to commit to a college. At kitchen tables across the country, anxious students and their parents are asking: Does it really matter where I go to school?

When it comes to lifetime earnings, we've been told, a bachelor's degree pays off six times more than a high-school diploma. The credential is all that matters, not where it's from—a view now widely accepted. That's one reason why college enrollment jumped by a third last decade and why for-profit...