We know that emotions are contagious. Research by UC San Diego’s James Fowler and Harvard’s Nicholas Christakis has shown that happiness is contagious, for example. If you have a friend who is happy, the probability that you will be happier rises by 25%.

We also know that behaviors are contagious. Christakis and Fowler determined that if you have overweight friends, you’re more likely to be overweight yourself. If you quit smoking, your friends are more likely to quit. Rose McDermott of Brown University found that divorce is contagious. She concluded that if you have a close friend who’s divorced, you are 33% more likely to split with your spouse.

We wanted to know how such "social contagion” affects leaders. We already know that good leadership creates engaged employees and that leaders influence a variety of outcomes such as personnel turnover, customer satisfaction, sales, revenue, productivity, and so on. But if you’re a good leader, do you make the people around you more likely to become good leaders as well? And which behaviors are most readily "caught”?

To answer this question, we examined 360-degree assessments of high-level managers and of their direct reports who were mid-level managers. Matching 265 pairs of high-level managers (HL) and their mid-level manager direct reports (ML), we found highly significant correlations on a variety of behaviors.

Specifically, we tested 51 behaviors and found significant correlations in over 30 of them. (All 51 showed some correlation, but not all the correlations were statistically significant.) Within the behaviors that appeared contagious, there were some that appeared even more contagious than others. Behaviors that had the highest correlations between managers and their direct reports clustered around the following themes, listed in order of most contagious to least contagious:

• Developing self and others
• Technical skills
• Strategy skills
• Consideration and cooperation
• Integrity and honesty
• Global perspective
• Decisiveness
• Results focus

We also examined overall performance. Unsurprisingly, the direct reports of the worst-performing HL managers were also below-average performers. Conversely, HL managers who were rated as very effective had ML reports who were also rated far above average. It could be argued that selection plays a role in these results, as in the old saying that "A players hire other A players, but B players hire C players.” However, an incumbent manager usually has personally hired fewer than a quarter of the people in their subordinate group. So we think this finding supports our hypothesis that leadership behavior is contagious: good HL leaders inspire better leadership behaviors among their ML reports, while bad HL leaders do the opposite.