The publication of the ninth edition of Yen & Jaffe marks another milestone in the history of this text, which has achieved a prominent place in the field of reproductive medicine. We were entrusted with the future of the book by its originators, who were giants in our field. Having done our best to meet their expectations, we now prepare for another transition in editorship of the text. With the publication of the ninth edition, we will be transitioning editorial responsibilities to Anuja Dokras, MD, MHCI, PhD, Carmen J. Williams, MD, PhD, and Zev Williams, MD, PhD, our co-editors of this edition.