Various methods for becoming a werewolf have been reported, one of the simplest being the removal of clothing and putting on a belt made of wolf skin, probably as a substitute for the assumption of an entire animal skin (which also is frequently described). In other cases, the body is rubbed with a magic salve. Drinking rainwater out of the footprint of the animal in question or from certain enchanted streams were also considered effectual modes of accomplishing metamorphosis. The 16th century Swedish writer Olaus Magnus says that the Livonian werewolves were initiated by draining a cup of specially prepared beer and repeating a set formula. Ralston in his Songs of the Russian People gives the form of incantation still familiar in Russia.

In Italy, France and Germany, it was said that a man or woman could turn into a werewolf if he or she, on a certain Wednesday or Friday, slept outside on a summer night with the full moon shining directly on his face.

Becoming a werewolf simply by being bitten or scratched by another werewolf as a form of contagion is common in modern horror fiction, but this kind of transmission is rare in legend, unlike the case in vampirism.

Even if the denotation of lycanthropy is limited to the wolf-metamorphosis of living human beings, the beliefs classed together under this head are far from uniform, and the term is somewhat capriciously applied. The transformation may be temporary or permanent; the were-animal may be the man himself metamorphosed; may be his double whose activity leaves the real man to all appearance unchanged; may be his soul, which goes forth seeking whom it may devour, leaving its body in a state of trance; or it may be no more than the messenger of the human being, a real animal or a familiar spirit, whose intimate connection with its owner is shown by the fact that any injury to it is believed, by a phenomenon known as repercussion, to cause a corresponding injury to the human being.