It used to be that college was a really big deal, a way to set yourself apart from 90 percent of your peers in the workplace. In fact, according to the U.S. Census Bureau, in 1947 only about 5 percent of Americans had a college degree, making it a major ingredient for success through the end of the last century. By 2008, however, 28 percent of Americans had a college degree, up from 5 percent half a century ago. The result is more competition and less differentiation for holders of a four-year Bachelor’s degree.

Not surprisingly, to keep or gain an edge in the workplace, many graduates began going back to graduate school starting in the early 1960s, especially for the coveted MBA degree. Since that time, the number of people holding MBA degrees has grown nearly 20-fold, from fewer than roughly 6,000 to more than 100,000, according to BusinessWeek. Of course, that means that graduate degrees, especially the more popular ones, are beginning to be so prevalent that they’re not worth what they used to be.

The bottom line is that if you are planning to attend grad school—which can easily cost $50,000-$100,000—you might want to rethink it if your primary motivation is income potential. The return on degree and return on major for this huge expenditure is heading south. The one notable exception are degrees that are needed to qualify for licensure or certification of some kind. From practicing medicine to social work to law, graduate degrees in these areas tend to be holding steady as far as both job prospects and pay.