When are collaboration and sharing bad for your team? When they're only being done by certain team members, with everyone else—including you—on the outside looking in. It's not that hard for an apparently solid team to break apart into a collection of cliques. Here's how you can stop this problem before it starts:
Identify the clique-prone. Sometimes, cliques are based simply on identity, with people of the same age, race or gender sorting themselves out from the others. Other factors to watch for may be prior work history—for example, if several team members used to work together somewhere else—or differences in work setting, such as between team members working in the office and those spending more time in the field. None of these factors is guaranteed to create a damaging clique, but they're important to recognize. Certainly, when you as the manager need to assign team members to work together, you should aim to avoid putting the naturally clique-prone together and giving them a reason to separate from the rest of the team.
Watch for clique creators. Sometimes these are people, but more often they're events or trends on your team. Any dramatic change in your work situation, such as a reorganization, a major new project or even instability at the top of the enterprise, can shake the team's foundations enough to create cliques. Also, if you're under pressure or managing a heavy workload, your people may not feel they have time to maintain social bonds with everyone on the team, let alone others in the enterprise. Hunkering down to deal with major challenges can lead to a "foxhole" mentality that's conducive to cliques.
Monitor your own behavior. It's your responsibility to promote effective relationships among the entire team, but as a manager you have more leeway to build those relationships than your team members might. The easiest way to make sure that people aren't being excluded is to include them yourself, and the easiest way to puncture a clique is to make yourself a part of it. Both of these strategies are part of your job description. And make sure that you're not, subconsciously, forming your own clique of your top team members, the people you turn to regularly for help with challenging tasks.