College enrollment boomed in recent years as people sought to upgrade skills and hide from a feeble labor market. But as the economy gains momentum, colleges are finding it harder to fill their classes—especially at community and for-profit colleges. Adults who enrolled in school because of a crummy job market are now being pulled back into the working economy. Enrollment fell by about 2 percent in the 2012–13 school year. Ivy Leagues, which will always have a willing population of attendees, will not feel the impact as much as the colleges we don’t see in U.S. News and World Report rankings. Many schools that rely largely on tuition dollars are concerned about keeping their doors open.