Summarize:

When talking to anyone representing your employer – whether it's a manager or someone in human resources – your attitude can make all the difference in how you are treated.  If you get angry and start lashing out, you may end up inadvertently proving the accuser correct. At the least, you'll give your employer a poor impression of your ability to handle conflict. Try to put yourself in the shoes of the person representing your employer. They are just doing their job and trying to get to the bottom of the situation. They're not your enemy – but if you treat them like your enemy, that may be what they become. If you find it difficult to handle the situation in person, ask if you may submit a written response. Being able to write it out enables you to approach the situation more calmly, without feeling like you're being interrogated. The more your employer relates to you as a person, the easier they'll find it to understand your side of the story. This doesn't mean you have to become the top office brown-noser. Just look for things you and the person with whom you're speaking have in common.  If you and your employer have something in common, bring it up. Just be careful not to bring it up in such a way that it looks like you're trying to avoid answering a question or change the subject. Some people are all business at work, and don't care for small talk or social chit-chat. If your employer isn't open to more social discussion, drop it. However, if you are able to focus on things you and your employer have in common, it can help your defense because they will see you more as a person like them. This can be especially helpful if the false accusation is related to harassment or behavior of a more personal nature (as opposed to violation of a workplace rule). You may be angry or indignant about the false accusations against you, and you may have some choice words to say about your accuser – but keep them to yourself. Bringing emotions into the situation or flinging back false accusations only muddies the waters.  False accusations can be more common when you and a coworker don't get along personally. It can be easy to get fired up about somebody you find annoying or vile, but it's important to keep a cool head when your job is on the line. Allegations and accusations are just that – statements that have not yet been proven true or false. Your employer is trying to get down to the truth of the matter. The best way to enable your employer to discover the falsity behind the accusation against you is to point to factual evidence that establishes your innocence. Depending on the type of accusations, your employer or the human resources department may launch a full-scale investigation to determine what really happened. Cooperating fully and making yourself available can help your situation.  Although the entire situation may be stressful, your full cooperation is the best way to ensure the situation is resolved quickly. If you balk or refuse to participate or answer questions, the investigation will stall. Without your participation, your employer may decide to believe the accusations are true. Your cooperation also signals to your employer that you are taking the situation – and your job – seriously. Your openness and willingness to discuss the accusations shows how much you care about maintaining a positive employment relationship. In some situations, especially if the false accusations are of a more personal nature, mediation can be beneficial. If you think it might help resolve your problem and protect your job, bring up the idea to your employer.  In mediation, a neutral third party works with you and your accuser in a safe, private environment. The mediator facilitates discussion that hopefully will lead to a mutually acceptable resolution for all involved. Many employers already have a mediation program in place for dealing with workplace disputes. If yours does not, you might want to suggest it to your employer. Keep in mind that for mediation to work, you have to keep an open mind about the situation. Even though the accusations may be false, you have to be willing to work with your accuser. This means you may have to accept some blame so that you can move forward, even if you know that you are completely innocent. While this can be a very difficult thing to do, it could potentially save your job. Particularly if you are classified as an at-will employee (and most employees in the United States are), you have limited rights when it comes to disciplinary sanctions at work.  For example, if your employer writes you up as a result of the accusation, you're not doing yourself any favors by refusing to sign the write-up notice. In fact, courts have held that an employee refusing to sign a write-up notice is sufficient cause to fire that employee for insubordination. You may have legal options you can pursue to clear your name. However, if you truly want to keep your job it's generally best to accept any disciplinary measures taken.
Remain calm, courteous, and professional. Establish a rapport. Stick to the facts. Cooperate with any investigation. Volunteer to participate in mediation. Accept the consequences.