Subheader: Selfish nastiness is all the rage, but research shows that pleasant behavior leads to more success and happiness in life.

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The great comedian Mel Brooks once contrasted comedy and tragedy. “Tragedy is when I cut my finger,” he said. “Comedy is when you fall into an open sewer and die.”

Mr. Brooks neatly encapsulates our current public culture of selfish nastiness. From this year’s ghastly presidential race, to the reality entertainment that spawned it, to the open sewer backing up from your Twitter feed, it looks like the worst behavior is being publicly rewarded, doesn’t it? You could be forgiven for believing that maybe the polarities of karma have reversed, and the world now belongs to jerks. Right?

Wrong. Nice people, rejoice: Notwithstanding the prominent examples today in political and popular culture, the best available research still clearly shows that in everyday life the nice people, not the creeps, do the best at work, in love and in happiness.

Let’s start with the job market. This has been another brutal year in which to graduate. Research from the Economic Policy Institute finds that young college graduates’ underemployment rate is nearly a third higher today than it was in 2007. Everyone is looking for an edge.

That edge is being pleasant and friendly. In one 2015 study published in the Journal of Applied Psychology, a team of scholars from France and the U.S. looked at the impact of civility and warmth to colleagues on perceived leadership and job performance. In addition to being seen as natural leaders by co-workers, nice employees performed significantly better than others in performance reviews by senior supervisors. For those who make it to leadership, niceness is also a key to success. A 2015 NBC poll found that most people would take a nicer boss over a 10% pay increase.

On the other hand, some researchers believe there are salary costs to being nice. In 2012, research published in the Journal of Personality and Social Psychology found that while those with high levels of “agreeableness” were less likely to be fired, they didn’t make the most money.

It is important to note that these researchers’ definition of agreeableness included “compliance” with the will of others. In many cases, however, compliance is not niceness; it is weakness. To be truly nice is not to comply when you disagree, but rather to disagree without being disagreeable. It isn’t to please at any cost, but rather to avoid being unpleasant even while standing up for what is right.

The benefits of being nice extend to love. In 2003, scholars from the University of South Carolina looked at the impact of being nice on perceived male attractiveness. They recruited 194 female volunteers to participate in a mock dating game in which they had to pick between two men, Todd and Mike. The researchers varied Todd’s levels of handsomeness and “niceness” while keeping Mike’s personality and looks constant and neutral.

The results were clear and conclusive. When their looks were equivalent, “Nice Todd” outperformed Neutral Mike. “Jerk Todd” lost 85% of the time to Mike even when Todd was better looking. In my view, the fact that niceness beats physical beauty is evidence of the existence of God.

But probably the greatest benefit of being nice accrues to one’s own happiness. In 2010, two British researchers looked at the effects of engaging in small daily acts of kindness. Their results, published in the Journal of Social Psychology, show clear causal evidence that kind acts, systematically deployed, raised the participants’ self-judged happiness.

It’s important to note that kindness and niceness are not identical. Kindness requires active generosity. But if you wonder whether the same experimental results will stand up, use yourself as a guinea pig. Deliberately set out to be nice for a week and see how it makes you feel. I’m confident you will like the result.

Can anyone learn to be nice? No doubt it is harder for some people than for others, but anyone can make progress and see benefits. One simple strategy for doing so is mimicry: Imitate the nicest person you know.

In my own case, that was my father. My dad died fairly young, at age 66. Hundreds of people who had known him over the years showed up at his funeral, and everyone I spoke to offered more or less the same observation: He was a truly nice man. Not a bad legacy, I thought. So I set out to imitate a few of his habits.

The most salient was his cheerful interaction with total strangers. He made banter with supermarket clerks, bellmen, bus drivers—everyone. “Hot enough for ya?” he’d ask, especially in winter. This mortified me as a child, especially when his friendliness so frequently went unrequited. But he didn’t care—if his clichés and corny jokes didn’t get a smile from one person, they might from the next. So now, to the chagrin of my own teenage children, I do the same. It has made me a happier person.

Niceness certainly is not a substitute for more active virtues like generosity and courage. But it’s a good start, and perhaps the easiest way to improve our lives. These days it is also a countercultural statement. To be nice is to subvert a pop culture that celebrates tactical nastiness—and instead choose a long-term personal strategy to build a happier life in a better world.

Mr. Brooks is president of the American Enterprise Institute.