The Wonderful Adventures of Nils is a work of fiction by the Swedish author Selma Lagerlöf. It was published in two books, which are here combined in a single volume.The background for publication was a commission from the National Teachers Association in 1902 to write a geography reader for the public schools. She devoted three years to Nature study and to familiarizing herself with animal and bird life. She has sought out hitherto unpublished folklore and legends of the different provinces. These she has ingeniously woven into her story.