Enemies to Allies: 6 Ways Employee Relationships Affect the Workplace

A recent study released by Cornerstone OnDemand in collaboration with Northwestern University gives new empirical weight to the old saying, “No man is an island.” While HR leaders have long believed that workplace relationships shape employee behavior, this research is among the first to quantify the organizational damage caused by toxic employees.

The report, Toxic Employees in the Workplace, finds that approximately 3–5 percent of employees are terminated for toxic behaviors such as misconduct, harassment, theft, substance abuse, or workplace violence. However, the most significant costs are not the direct ones—rather, they stem from the ripple effects toxic individuals have on their coworkers.

Employees who work alongside toxic colleagues are significantly more likely to leave the organization or engage in similar negative behaviors themselves. This research is part of a broader body of evidence showing that the social fabric of the workplace is just as important to tenure and performance as job design or pay.

Cornerstone refers to this phenomenon as the “friendship effect”—the measurable impact that workplace relationships, whether positive or negative, have on employee outcomes.

Below are six evidence-based ways employee relationships influence the workplace:

1. Toxic coworkers drive attrition. Employees are up to 54 percent more likely to quit when the number of toxic employees increases by just one on a team of twenty.
2. Referred employees are stronger hires. Research with the University of Toronto’s Rotman School of Management shows that referred employees are 8–20 percent less likely to quit and are often less likely to engage in workplace misconduct.
3. Friendship predicts retention. Employees who know three or more coworkers at their company tend to stay significantly longer than those with fewer social connections.
4. Social networking correlates with productivity. Employees who use up to four social networks at work handle customer interactions faster, close more sales, and remain employed longer than those who use none.
5. Socially engaging trainers drive better outcomes. Training programs that foster camaraderie and interaction lead to two to three times longer employee tenure than less socially oriented environments.
6. Supervisors matter most. An employee’s first manager is the single strongest predictor of long-term performance and retention, even years into their career.

Advances in people analytics now allow organizations to measure and act on these social dynamics at scale. During hiring, science-based assessments can help identify candidates who are not only qualified, but also less likely to exhibit toxic behaviors. For example, candidates rated as highly qualified by Cornerstone Selection are 19 percent less likely to be terminated for policy violations.

Beyond hiring, analytics can guide the design of programs that strengthen workplace relationships—such as mentorship initiatives, team-based learning, community lunches, and informal social events—ensuring they are optimized for long-term impact rather than intuition alone.

The broader implication is clear: employee relationships are not a “soft” variable. When measured rigorously and acted on thoughtfully, they become a powerful lever for improving retention, performance, and organizational health.