A differential roll printing strategy is developed to enable large-scale and uniform assembly of highly aligned and ordered nanowire arrays on various rigid and flexible substrate materials. The dynamics of the process are explored by tuning the linear sliding motion of the roller with respect to the rolling motion, clearly demonstrating the importance of the differential rolling process in the controlled assembly of nanowires. The potency and versatility of the method is further demonstrated by fabrication of nanowire transistor arrays on flexible substrates. © 2007 American Institute of Physics.