In His Steps is a best-selling religious fiction novel written by Charles Monroe Sheldon. First published in 1896, the book has sold more than 30,000,000 copies, and ranks as one of the best-selling books of all time. The full title of the book is In His Steps: What Would Jesus Do?

Though variations of the subtitle "What would Jesus do" have been used by Christians for centuries as a form of imitatio dei, the imitation of God, it gained much greater currency following publication of the book.

Chicago Advance, the original publisher, failed to register the copyright in the proper form. Other publishers took advantage of this, publishing the book without paying the author royalties. Thus lower prices and multiple publishers led to larger sales. (wikipedia.org)