Clothing provides protection from the environment; it conveys passion, in the sense that it communicates the personal style of the wearer; it is pervasive-virtually every culture around the world uses it in some form; and it is a passive medium. Today, however, there is a growing proportion of active and dynamic individuals seeking connectivity and interactivity with surrounding objects and the environment. A well-designed information-processing system should facilitate access of information anytime anyplace by anyone. The ultimate information-processing system would not only provide for large bandwidth, but also have the ability to see, sense, think, and act. Such a system should be totally customizable and in synch with the human user. Since clothing, in most cultures, presents a "universal" interface, 1 it has the potential to meet this emerging need of today's consumers. Also, textiles provide the ultimate flexibility in system design by virtue of the broad range of fibers, yarns, fabrics, and manufacturing techniques that Abstract Protection and aesthetics are the two common dimensions or attributes typically associated with textiles as clothing. However, with the rapidly changing needs of today's consumers, a third dimension is emerging-that of "intelligence"-that is being integrated into fabrics to produce interactive textiles, or i-textiles. This new class of wearable electronic systems is being designed to meet new and innovative applications in the military, public safety, healthcare, space exploration, sports, and consumer fitness fields. In this article, the concept of i-textiles is presented, along with the building blocks for its realization. This is followed by an overview of the design and development of the Smart Shirt, an "intelligent" garment that provides an extremely versatile framework for the incorporation of sensing, monitoring, and information-processing devices. The key applications of the Smart Shirt technology and their impact in transforming healthcare are discussed. Finally, the need to advance this paradigm and identify opportunities to transform passive textiles into the new generation of interactive, or "smart," textiles is discussed.