Daniel S. Hamermesh, a professor of economics at the University of Texas, Austin, is the author of "Beauty Pays," published this month.

BEING good-looking is useful in so many ways.

In addition to whatever personal pleasure it gives you, being attractive also helps you earn more money, find a higher-earning spouse (and one who looks better, too!) and get better deals on mortgages. Each of these facts has been demonstrated over the past 20 years by many economists and other researchers. The effects are not small: one study showed that an American worker who was among the bottom one-seventh in looks, as assessed by randomly chosen observers, earned 10 to 15 percent less per year than a similar worker whose looks were assessed in the top one-third — a lifetime difference, in a typical case, of about $230,000.

Beauty is as much an issue for men as for women. While extensive research shows that women’s looks have bigger impacts in the market for mates, another large group of studies demonstrates that men’s looks have bigger impacts on the job.

Why this disparate treatment of looks in so many areas of life? It’s a matter of simple prejudice. Most of us, regardless of our professed attitudes, prefer as customers to buy from better-looking salespeople, as jurors to listen to better-looking attorneys, as voters to be led by better-looking politicians, as students to learn from better-looking professors. This is not a matter of evil employers’ refusing to hire the ugly: in our roles as workers, customers and potential lovers we are all responsible for these effects.