My colleagues and I recently studied what happens to individuals, teams, and entire organizations when underperformers infiltrate the office. We found that 93 percent of employees report working with people who don't pull their weight.

Even more disturbing is what doesn't happen when it comes to dealing with a slacker: Only 10 percent of the workforce speaks up and holds underperforming colleagues accountable.

Goodwill isn't the only victim of slacking co-workers—we found that productivity, satisfaction, and quality also suffer. Specifically, slacking co-workers cause a quarter of their hard-working colleagues to put in four to six more hours of work each week. And according to four out of five of these hard workers, the extra time invested causes a decline in the quality of their own work.

When it comes to confronting a slacking co-worker, most people assume the conversation isn't worth having. This "epidemic of silence" shows that people aren't considering the risks of not speaking up.

It's time training professionals equip employees with the skills to candidly and respectfully hold co-workers accountable. Here are a few skills you can teach to begin building a culture where bad behavior isn't tolerated.

• Suspend judgments and get curious. Perhaps your co-worker is unaware of the effects of his actions. Enter the conversation as a curious friend rather than an angry co-worker.

• Make it safe. Don't start by diving into the issue. Establish safety by letting your co-worker know you respect him and reminding him of the mutual goals you share.

• State facts and describe the gap. Start with the facts of the issue and strip out accusatory, judgmental, and inflammatory language. Then, explain the gap between what was expected and what was delivered.

• Tentatively share concerns. Having laid out the facts, tell your co-worker why you're concerned. Help him to understand the natural consequences of his actions.

• Invite dialogue. Next, ask if he sees the problem differently. If you are open to hearing others' points of view, they'll be more open to yours.