First, the tough news. Once you're in a supervisory position, that is the primary relationship you have to people, even if you're also friends with them outside of work. You can't turn off your boss role at will. This is a bummer even when you're new to the company, but it creates all kinds of complications when you are promoted from within. Suddenly all your previous relationships with your team, those you get along great with and those you maybe don't, take on a whole new tone. Even if you'd like things to stay mostly the same, it's important to realize that having the power to influence people's careers and livelihoods changes your dynamic with them. It's also important to remember that your new role gives you access to information that might not be appropriate for you to share with your employees, even if you trust them to keep it to themselves.
So, what does this mean in practice? It doesn't mean that you can't be friendly with your employees, but it does mean you have to be careful about being friends with them, especially if you're singling out one or two people and not the others. If you want to play it totally safe, consider the following best practices.
Best practices for managing people who used to be your peers
Don't hang out with employees outside of work unless you include all of them. You might be able to ease up on this later once you've solidly established yourself as a leader, but for now this is a safe approach.
If you go to happy hour with your employees, keep it to one drink. This is both a professionalism thing as well as a timing thing (once you leave, it sort of gives others permission to leave as well), so it applies even if you're not drinking alcohol.
Make a conscious effort to treat employees as consistently as you can. That doesn't mean you treat them all the same, but any strictness or flexibility is universally applied, and your decisions should be grounded in work-related logic rather than personal bias. For example, if you allow one employee to work a flexible schedule, your decision about whether to allow another employee to telework should be based on the same work-related criteria rather than personal considerations.
Be transparent about why you choose certain people for certain projects. Make it clear that the decisions are based on business reasons, not relationships. For example, if you assign an undesirable project and it happens that the lucky assignee is someone you didn't get along with all that well before your promotion, it will be very important to communicate to them, the team, and possibly even yourself why this is a good business decision. (Thinking through beforehand what you'll say to justify the decision will help you make sure it is truly justified, too.)
Be aware that we tend to gravitate toward people who are similar to us and whom we trust, and we give them the benefit of the doubt in a way we don't do for those who seem less similar. This is a natural bias, so the best way to deal with it is to get to know each of your employees, especially the ones you don't like as much. Assuming they're actually doing their job, there must be something valuable that they add to the team and something interesting about them as a person. Make an effort to figure that out and to better understand where they're coming from. This will help you view them more favorably just because you know them better, and it is a better alternative than withdrawing from the people you like. It's also going to help them trust you more, which makes many aspects of your job much easier.
Think carefully about connecting or staying connected with any of your employees on social media. If you are connected to some of them but not others, that looks like favoritism and will result in inside jokes and shared understanding that others on the team aren't privy to. However, if you're connected to your whole team, that will increase the oppressive feeling of being "The Boss" all the time and having to filter what you say or do in that space as well as at work. It's your call as to what makes the most sense for your situation.
Keep in mind that you're the boss now, and that colors every interaction you have with your employees. It sucks sometimes, but that's how hierarchy works. It's possible to be friends with your employees - in fact, it makes work a lot more fun - but you need to be careful to ensure you're being even-handed with all of your employees and still maintaining your credibility as the team leader. Consider building relationships with your peers. This is a safer bet and can be a great support network for you.
Can you be friends with your boss? post by Karen Dillon on hbr.org.
This is a somewhat more optimistic take, but from the employee's point of view. It's good food for thought.
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