Superstars get a lot of attention from bosses. But bad apples deserve even more.

A growing body of research suggests that having just a few nasty, lazy or incompetent characters around can ruin the performance of a team or an entire organization — no matter how stellar the other employees.

Bad apples distract and drag down everyone, and their destructive behaviors, such as anger, laziness and incompetence, are remarkably contagious. Leaders who let a few bad apples in the door — perhaps in exchange for political favors — or look the other way when employees are rude or incompetent are setting the stage for even their most skilled people to fail.

It's crucial for leaders to screen out bad apples before they're hired—and if they do slip through the cracks, bosses must make every effort to reform or (if necessary) oust them.

Spreading the Vibes

It's easy to understand why bosses would rather focus on attracting and developing superstars. A mountain of research shows that stars and geniuses can deliver astounding results. And, obviously, it's more fun and inspiring to focus on top-performing, energetic employees.

But studies of everything from romantic relationships to workplace encounters show that negative interactions can pack a much bigger wallop than positive ones. The reason is simple: "Bad is stronger than good," as psychologist Roy Baumeister and his colleagues put it. The negative thoughts, feelings and performance they trigger in others are far larger and longer lasting than the positive responses generated by more constructive colleagues.

Consider research on bad apples and team effectiveness by Will Felps, Terence R. Mitchell and Eliza Byington. They examined the impact of team members who were deadbeats ("withholders of effort"), downers (who "express pessimism, anxiety, insecurity and irritation") and jerks (who violate "interpersonal norms of respect"). An experiment by Mr. Felps found that having just one slacker or jerk in a group can bring down performance by 30% to 40%.

How can organizations squash those negative influences? The easiest way, obviously, is to avoid hiring bad apples in the first place—and that means taking a different approach to assessing candidates for jobs.

The usual means of screening are often weak when it comes to determining if a job candidate is a bad apple. Candidates may have gone to the best schools or may come across as charming and brilliant in interviews—thus disguising their laziness, incompetence or nastiness.

That's why one of the best ways to screen employees is to see how they actually do the job under realistic conditions. Akshay Kothari and Ankit Gupta favor that approach. When they're hiring new people for their Palo Alto, Calif., company, Pulse, which makes a news-reading app for mobile devices, they consider evaluations from peers and superiors and do multiple rounds of interviews. But they say the most effective thing is to bring candidates in for a day or two and give them a short job to accomplish. (The candidates are paid for their time.)

Not only do they learn a lot about the candidates' technical skills, Messrs. Kothari and Gupta say, but they also learn about their personality. How do they deal with setbacks? Do they know when to ask for help and to give others help? Is the candidate the kind of person they want to work with? The partners say there have been several candidates who looked great on paper and came highly recommended but weren't offered jobs—because technical and interpersonal weaknesses surfaced during the selection process.

Play Nice or Else

Beyond smarter screening, it's important to develop a culture that doesn't tolerate jerks. The best organizations make explicit their intolerance for bad apples; they spell out which behaviors are unacceptable in the workplace and act decisively to prevent and halt them.

Consider Robert W. Baird & Co., a financial-services firm that has won praise as a great place to work. The company is serious about creating a culture where disrespect and selfishness are unacceptable. They call this the "no jerk rule" (though they use a more colorful word than "jerk").

The company starts sending the message during the hiring process, says CEO Paul Purcell. "During the interview, I look them in the eye and tell them, 'If I discover that you are a jerk, I am going to fire you,' " he says. "Most candidates aren't fazed by this, but every now and then, one turns pale, and we never see them again—they find some reason to back out of the search."

When the company makes a hiring error and brings aboard an employee who persistently demeans colleagues or puts personal needs ahead of others, Baird acts quickly to deal with or expel the bad apple.

Mr. Purcell's crusty approach won't work in every company culture. For an idea of how to handle the task with a more subtle hand, look at renowned chef Alice Waters, who has headed the restaurant Chez Panisse in Berkeley, Calif., for 40 years now.

Biographer Thomas McNamee describes how Ms. Waters's love of people and food has spread to those around her. Along the way, though, many bad apples have been shown the door — but Ms. Waters doesn't hold it open. The process usually starts when one of her colleagues conveys the message that Ms. Waters isn't "entirely pleased." If the hints don't work, then that colleague — or someone else close to Ms. Waters — does the firing.

A spokesman for Chez Panisse says Ms. Waters does personally fire employees on occasion and "she manages to have that person feel as though they are making the decision to leave and it is better for themselves to move on and explore new opportunities." He also notes that a large percentage of employees have been with the restaurant for decades.

Keeping Them Close

There are times, of course, when an organization can't — or won't — remove a destructive personality. Maybe the person is a star as well as a bad apple, for instance, or is otherwise crucial to the operation. In such cases, leaders might try to use coaching, warnings and incentives to curb the toxic employee's behavior. Another tactic is to physically isolate the bad apple.

In one organization, there was a deeply skilled and incredibly nasty engineer whom leaders could not bring themselves to fire. So, they rented a beautiful private office for him several blocks from the building where his colleagues worked. His co-workers were a lot happier — and so was he, since he preferred working alone.

But beware: Leaders who believe that destructive superstars are "too important" to fire often underestimate the damage they can do. Stanford researchers Charles O'Reilly and Jeffrey Pfeffer report a revealing episode at a clothing retailer. The company fired a top-producing salesman who was a bad apple. After he was gone, none of his former colleagues sold as much as he had. But the store's total sales shot up by nearly 30%. The lesson, according to the researchers: "That one individual brought the others down, and when he was gone, they could do their best."

Mr. Sutton, a professor of management science and engineering at Stanford University, is the author of "Good Boss, Bad Boss: How to Be the Best…and Learn from the Worst." He can be reached at reports@wsj.com.