This book presents the proceedings of NI 2021, the 15th International Congress in Nursing Informatics. Originally planned to be held in 2020, the international year of the nurse and midwife, but postponed due to the SARS-CoV-2 pandemic, the conference, with the theme of nursing and midwifery in the digital age, was eventually held as a virtual event from 23 August to 2 September 2021, and the organizers made the decision to take advantage of its virtual nature and extend it to 9 days, with each day focusing on a different theme. This is reflected in the organization of the book, and the 212 papers included here, of which 67 are full papers with the remainder being workshop, panel, case study, and poster abstracts, are grouped into 9 sections. The papers were selected from a total of 437 submissions from more than 40 countries and cover: data analytics and the use of nursing data; digital health nursing workforce development; health policy, service delivery and ethics; informatics in clinical care; innovation and entrepreneurship in nursing; integrated and connected care; nursing information systems; patient participation and citizen involvement; and systems implementation and digital workplaces.