I have been deeply amazed and grateful to see how the Case Files^® books have been so well received and have helped students to learn more effectively. In the 17 years since Case Files^®: Obstetrics and Gynecology first made it in print, the series has now multiplied to span most of the clinical and basic science disciplines and has been translated into nearly 20 foreign languages. Numerous students have sent encouraging remarks about the changes in the fifth edition, which was divided into obstetrics in the first half and gynecology in the second half to be more “user-friendly” during the clerkship because most students have their rotation divided into those two categories. In this sixth edition, we have retained the grouping of related cases closer together to allow students to use information from one case to reinforce principles to another case, and we have cross-referenced related cases. Although space is always a premium, we have also retained and expanded Section III, which is a collection of strategic questions that can be used not only for review but also to tie in principles from the cases. Questions have been improved to better reflect the USMLE format, and explanations have been expanded to help the student understand the mechanisms and the reasons that the other choices are incorrect. Many cases are new or have been completely rewritten (Induction of Labor and Trial of Labor After Cesarean; Genetic Screening and Teratogens; Postpartum Depression, Opioid Use Disorder, and Maternal Mortality; Gender Identity; Uterine Fibroids/Abnormal Uterine Bleeding; Patient Safety and Medical Error; Septic Abortion and Elective Termination of Pregnancy; Vulvar Disorders; Anemia in Pregnancy [Folate Deficiency]; Pelvic Organ Prolapse; and Chronic Pelvic Pain and Endometriosis). This sixth edition has been a collaborative work with my wonderful coauthors and contributors and with the suggestions from six generations of students. Truly, the enthusiastic encouragement from students throughout not just the United States but worldwide provides me with the inspiration and energy to continue to write. It is thus with humility that I offer my sincere thanks to students everywhere . . for without students, how can a teacher teach?