The king sets his three sons (or an old peasant woman, her sons, in Lang''s version) to marry, and tests their chosen brides.
The king may set them to shoot arrows and find their brides where the arrows land, and the youngest prince''s arrow is picked up by a frog; the two older sons may already have girls picked out, but the youngest son -- Ivan Tsarevich in the Russian -- is at a loss until a friendly frog takes pity on him and offers to marry him. In Calvino''s version, the princes uses slings rather than bows and arrows. In the Greek, the princes set out to find their brides one by one; the older two are already married by the time the third sets out
The king then assigns his three prospective daughters-in-law various tasks, such as spinning cloth and baking bread. In every task the frog far outdoes the lazy brides-to-be of the older brothers; in some versions, she uses magic to accomplish the tasks, the other brides attempt to emulate her and can not do the magic. Still, the young prince is ashamed of his froggy bride, until she magically is transformed into a princess.
In the Russian, the last test may be of dancing, with the frog bride having shed her skin; the prince then burns it, to her dismay. If he had waited, she would have been free, but he has lost her. He then sets out to find her again and meets up with Baba Yaga, whom he impresses with his spirit, demanding to know why she has not offered him hospitality. She may tell him that Koschei has his bride captive, and how to find the magic needle, without which Koschei will be helpless; with that, he rescues his bride. In others, his wife flies into Baba Yaga''s hut as a bird; he catches her, she turns into a lizard, and he can not hold on. Baba Yaga rebukes him and sends him to her sister; there he fails again, but is sent to the third sister, where he catches her, and no transformations break her free again.
In some versions of the story, the transformation is a reward for her good nature; in others, she is transformed by witches out of amusement; and in others, she is revealed to have been an enchanted princess all along.