Discouraged, but permitted. It is effected by a document called a get. By Jewish law, a husband must present a wife with a get of his own free will, and traditionally (but not by law) she must choose to accept it. The former presents an obvious problem when a wife wishes to be divorced but her husband does not. This is a considerable problem in observant Jewish communities and has led to a variety of attempted solutions of varying acceptance and effectiveness (usually in the form of some sort of prenuptial agreement, but occasionally more creative, less legal forms).