If you've worked with the same company for several years, you've probably built many friendships. Some of your coworkers might be close friends, while others are individuals with whom you might share a weekend story on Monday morning. A friendship at work can become a powerful networking tool or a toxic relationship. What works best when you are in a leadership position?

"In general, casual -- not close -- friendships are preferable in business.... Casual ones are safest, but carefully managed close or best ones will also help," says Dr. Jan Yager, author of Business Protocol. In her survey of 126 human resource managers, 37 percent said they got their current job through someone they knew, and 25 percent said they got their job through a close friend or family member. So close or distant friendships can be a real advantage.

How Do You Make Friendships Work at Work?

To maintain dignity and respect in your leadership position, you need to follow a few important tips.

• Set Parameters with Close Friends: Sit down and talk with your friend about how you will work together. Make it clear that you do not intend to extend special favors. Also make it clear that your close friend should refer to you the same way other employees do while you are at work. Let your friend know that when you are away from work, you prefer not to discuss work situations involving him.
  
• Be Careful Whom You Trust: It is very important to take your time building friendships at work. Watch and see which individual seems to be the person that other employees confide in and who seems to click with whom. It takes time to build trust, so don't start confiding top secrets to a new person right away. Share small, insignificant confidences at first to test the waters.
  
• Be Fair to All Your Subordinates: Don't totally deprive your friend of promotions just because of your friendship. If your friend is the most qualified, give him the big project. If your friend is equally qualified with others in the group, alternate who gets the big project. Do yourself a favor: If you think you will be biased, ask someone else to make the final decision for you.
  
• Manage Your Own Credibility: If it is known in your organization that you are close friends with a particular coworker, you may be overlooked for additional promotions, because it could be feared that you would divulge confidences to your friend. Be careful not to let your close friendships show at work.
  
• Build New Friendships Outside of the Company: You don't have to disown your friends at work, but it is a good idea to develop other friendships outside the company. When you need a person to be a sounding board or to fine-tune your own style, it is better to confide in a friend who is not personally interested in the company.

How Can You Keep Your Distance at Work?

While there's evidence that workplace friendships can have a positive effect, do you really need to have your best friend working beside you all day long?

If you have developed friendships at work, make it a practice to avoid wild parties and constant happy hours with the gang. Go have a drink to show you are part of the team, and then make a quick exit.

Finally, find yourself a mentor within the company. Typically, a mentor is someone who is older and wiser -- someone who can show you the ropes. Developing such a relationship can help you avoid spending too much time with your friends. This relationship also will help your career. Then, if you're lucky, your mentor will become a lifelong friend, too.