Kawasaki disease (KD) is the archetypal pediatric vasculitis, exemplifying the unique aspects and challenges of vascular inflammation in children. The condition is almost unheard of in adults, is closely associated with infections, and is self-limited, with fever resolving after an average of 12 days even without treatment. Yet KD is also a potentially fatal disease and the most common cause of acquired heart disease in the developed world. Unraveling of the developmental, immunologic, and genetic secrets of Kawasaki disease promises to improve our understanding of vasculitis in particular, and perhaps also to provide a window on the fundamental mysteries of inflammatory diseases in general.