Whether it's a coworker who won't quit commenting on your appearance or a supervisor who is demanding that you do labor you were never hired to do, workplace harassment is all too real. It can damage you personally, sidetrack your career and even get you fired. But harassment is a damaging accusation to make, so if you're going to blow the whistle, you need to take proactive steps so that you can prove your case to your boss or in court.
Identify exactly what harassment is occurring. At this stage, it can be helpful to talk over the situation calmly and thoroughly with a trusted friend or clergy member. Write down specific instances of inappropriate behavior. When someone is harassing you at work, it's easy to get emotionally worked up and see everything she does as harassment. At this point, your job is to get help working through the situation and seeing it from a calm, realistic point of view. Your friend can probably give you good insight into what is happening and keep you from making rash accusations based purely on emotion.
Get a calendar that you will use to document every instance of harassment. The next time your coworker says those mean things, write the time and date in your calendar. The next time your boss embarrasses you by cutting you down in front of your coworkers, document that. Don't be petty, but you need to write down any serious infraction. This is so that when you do make the accusation of harassment, you will have specific acts to point to. This documentation will avoid a "he said, she said" type of argument.
Save any communications from the offending party. For example, if your supervisor is asking you to do something unethical, save those emails and memos. If he is savvy enough to avoid leaving a paper trail, request that all communication from him be in written form. This alone may solve your problem. But if it doesn't, it will at least give you ironclad proof.
Talk to your coworkers. Chances are, the fact that someone is harassing you is an open secret at your workplace. You may find that your coworkers are sympathetic. Ask them to testify on your behalf. A caveat is in order here, though: As much as people may like you, few are willing to take on a fight like this, so be prepared to go through with the claim without their support. Never assume that they will back you up. Many times, they will agree with you until it is time for them to take any risks themselves.
Be a model employee. When the time comes to prove that you are being harassed, nothing speaks as loudly as good behavior. Overbearing bosses and out-of-control employees are usually known to everyone. If you keep your documentation, note the time and place of the harassment and perhaps get support from your coworkers, you should easily be able to prove workplace harassment to your boss' supervisor or a government official.
Stick to the facts of the case. Resist the urge to make it personal or tell the person in charge or investigating your complaint that the boss "has it in for you."
Never complain about harassment unless you are absolutely sure it is true. This can jeopardize your career.