This book presents selected papers from the 4th International Conference on Functional Textiles and Clothing Conference (FTC 2025) held at the Indian Institute of Technology (IIT) Delhi. This book provides an overview of the latest developments taking place in the field of circular and sustainable textiles and apparel, including applications of nano technology, dry finishing technologies and new materials that are stretching the frontiers of textile industry. This book discusses the emerging area of 3D design of clothing, and testing and evaluation of functional clothing. The challenges facing the craft sector in India and interventions made to revive the same are also covered here. The book will serve as a good reference for researchers working in the emerging area of Functional clothing and Textiles.