Having colleagues who are good friends too is always a bonus. It makes going to work, and getting through tough days, that bit easier. A supportive, friendly environment also improves morale and teamwork.
However, there's a thin line between having friends at work, and being part of a clique. The former situation is positive and fosters a productive climate, while the latter is negative and generates a polarising work environment.
What's the difference?
Good colleagues don't edge over the line into exclusive cliques or turn friendships into political alliances. For instance, it's one thing to enjoy having lunch together, but quite another to react badly when one member of the regular lunch party chooses to eat with another colleague the others don't like.
It's fine for people to be able to share their personal problems with close co-workers, but it stops being all right when these problems are used as weapons to subtly keep a clique member in line, or as excuses for burdening co-workers with the "sufferer's" job responsibilities.
Having a little giggle over things that happen in the workplace is a good way of relieving stress, but it's something else altogether to launch into exchanges of full-blown gossip, malicious rumours, backstabbing and ganging up to make life hard for someone your crowd dislikes. That's playground behaviour, highly immature and very unprofessional.
Tread carefully, especially when you are new to a workplace. Neither carelessly offend others nor be too swiftly absorbed by a group.
Don't join cliques. It's best to stay neutral. You can be good friends with someone without having to be part of their hard-and-fast crowd. Joining a clique is sure to affect your objectivity, which could in turn affect your work and even your promotion prospects.
Don't get too personal too fast, even if someone feels like a soulmate. Initially divulge harmless general information about your family, hobbies or food preferences. Don't go deep right from the start into your 20 years of therapy, your son's juvenile delinquent record, or how you're still devastated by the death of your father, who passed on 10 years ago. Only when enough time has gone by, and you've grown genuinely close to some co-workers, will you know whom you can trust with such information.
Some enmities between established co-workers are so entrenched that certain individuals see every new colleague as a potential recruit to "their side". These people will from day one try to poison your mind against someone else in the company. The tricky bit is that they could well be right about the person being demonspawn. However, the point is that it is not for them to turn you against him or her. Stay neutral for as long as possible with all parties. Maintain a firm, gentle and polite approach to all - without getting too friendly.
Alternate your lunch kaki. If you enjoy certain people's company, by all means join them more often. But make it a point to occasionally have lunch with someone else, or by yourself, so that lunching with a particular crowd is not an obligation you have to "the gang", but a pleasure.