The framers of the Declaration of Independence evidently believed that happiness could be achieved, putting its pursuit up there alongside the unalienable rights to life and liberty. Though governments since then have seen life and liberty as deserving of vigorous protection, for all the public policies aimed at increasing economic growth, people have been left to sort out their happiness.

This is an unfortunate omission. Despite all the wealth we have accumulated — increased life expectancy, central heating, plasma TVs and venti-white-chocolate-mocha Frappuccinos — true happiness has lagged our prosperity. As Bobby Kennedy said in a speech at the University of Kansas in March 1968, the nation’s gross national product measures everything “except that which makes life worthwhile.”

The era of laissez-faire happiness might be coming to an end. Some prominent economists and psychologists are looking into ways to measure happiness to draw it into the public policy realm. Thirty years from now, reducing unhappiness could become another target of policy, like cutting poverty.

“This is another outcome that we should be concerned about,” said Alan Krueger, a professor of economics at Princeton who is working to develop a measure of happiness that could be used with other economic indicators. “Just like G.D.P.”