Q: “For the past few weeks, one of my co-workers has been watching me closely and finding fault with my work. She keeps telling me what to do, even though she’s not my supervisor. I actually have more experience than she does. Should I tell my manager about this? I don’t want him to think I’m complaining.” Jenny
A: Before going to your boss, try talking directly with your intrusive colleague. Since this monitoring behavior is new, something must have triggered it, so perhaps you can find out what’s wrong. The next time she corrects you, inquire about the reason for her concern.
For example: “Mary, I’ve noticed that lately you seem to be unhappy with my work. Am I doing something that bothers you?” If she says yes, try to resolve the issue. But if the answer is no, just tell her you’re glad that everything’s okay, then see if she ends her surveillance.
Should the scrutiny continue, you will need to become more assertive: “Mary, you and I apparently have different ways of doing things. I’m comfortable with my own approach, and I have no reason to change.” After delivering this mild admonition, stop responding to any further criticism.
If her pestering continues to be a problem, then it’s time to go to your boss. After describing the situation in a calm, businesslike manner, ask if he will remind “Mary” that you already have a supervisor.
If you need to give some feedback to a coworker or friend, here's the way to do it: How to Give Feedback without Criticism.