1) IF you have a valid cause of action, then quitting does not mean you can't pursue it--though it could reduce what you might win. For example, say you feel that you are discriminated against on a racial basis and are underpaid. If you voluntarily quit, depending on the circumstances, you may only be able to recover additional compensation up to when you quit (if your forced out, that's a different story; but if it's merely unpleasant, you might have to stick it out to sue for money going forward).2) However, no all hostile environments or discrimination are actionable. In brief, a workplace can be hostile to employees, and it can treat them differentially or unfairly and discriminate, with this exception: it can't discriminate on the basis of a specifically legally protected characteristic, such as an employee's race, religion, age over 40, sex, or disability. Discrimination on those bases can give rise to liability; but simply discriminating against an employee who a supervisor doesn't like is not illegal.If you  feel you may be the victim of illegal discrimination, you should consult with an employment attorney before taking any action.