This book offers a comprehensive, systematic presentation of the interdisciplinary research process and the theory that informs it by drawing on student and professional work from a variety of fields. The book has been iterative in its development over editions, as the authors have learned from the work of instructors and students using it and have adjusted their advice in response. Notable changes in the Fifth Edition respond to feedback from the Forum devoted to this book in Issues in Interdisciplinary Studies in 2022. Examples have been updated so most are more contemporary, new content has been added on mixed methods and team research to respond to the needs of graduate students, and content has been revised throughout to address the current thinking on interdisciplinarity and integration, and strategies for achieving common ground as an interdisciplinary research team.An instructor website for the book at http://edge.sagepub.com/repko5e includes editable PowerPoint slides, a test bank, and figures and tables from the book.