Sexual harassment is forbidden by both state and federal law. The Civil Rights Act of 1964 actually outlines the parameters of sexual harassment at work under Title VII. According to this title, there are two ways that sexual harassment at work can occur: either under a quid pro quo basis, or in an hostile work environment.
Quid pro quo sexual harassment is when someone at work -- presumably someone in a position of power or authority -- makes sexual advances or sexually harasses towards another employee while making it it clear that their job, or their benefits, or their potential promotion is on the line in the process. In other words: tolerate this sexual harassment, or you will be fired.
Hostile work environment is pretty straight forward, and it doesn't always involve sexual harassment. But when an employee sexually harasses someone continually and with no repudiation by the company or supervisors, then the situations can constitute a hostile work environment. When this occurs, the victim of the sexual harassment should consider his or her legal options because a hostile work environment opens the employer up to liability.
However, remember that Title VII also says that companies with 14 or fewer people are not subject to the federal law. That is where state law takes over. This can create legal complications in sexual harassment cases.
No matter the specifics of your case, if you have been sexually harassed at work -- whether it is quid pro quo or a hostile work environment -- you should consult with a lawyer immediately.