Authoring, its tools, processes, and design challenges are key issues for the Interactive Digital Narrative (IDN) research community. The complexity of IDN authoring, often involving stories co-created by procedures and user interaction, creates confusion for tool developers and raises barriers for new authors.This book examines these issues from both the tool designer and the author's perspective, discusses the poetics of IDN and how that can be used to design authoring tools, explores diverse forms of IDN and their demands, and investigates the challenges around conducting research on IDN authoring.To address these challenges, the chapter authors incorporate a range of interdisciplinary perspectives on 'The Authoring Problem' in IDN. While existing texts provide 'how-to' guidance for authors, this book is a primer for research and practice-based investigations into the authoring problem, collecting the latest thoughts about this area from key researchers and practitioners.