If you find out that you are making less money than a co-worker who is doing the same or similar work, you may be able to sue your employer if their reasoning is illegal. You should first discuss this with your employer if you feel safe to do so. Remember, if you do bring this up with your employer, they cannot fire you, demote you, reduce your pay, reduce your work hours, or take any other adverse action against you for bringing this issue to their attention.