This book explores how novel digital services, including e-services, digital platforms and mobile apps, are increasingly being innovated through open processes. It investigates how and why organizations invite external developers to participate in their innovation, often catalyzed by contests and the provision of open data, with the aim of designing digital services that go beyond the capability of the organizations themselves. Taking a contest driven approach to innovation, the book provides an accessible yet comprehensive introduction to the area of open digital innovation. It offers an analysis of key scientific principles underlying open innovation and based on these provides practical tools for improving the digital innovation process. Furthermore, the book introduces instruments for managing innovation contests, in particular for overcoming innovation barriers and for harnessing the power of motivating factors. It serves as a text for graduate and undergraduate courses in digital innovation and entrepreneurship, but is also a valuable resource for managers as well as policy makers in the field of open digital innovation.