Supercrystals of uniform nanorods and ordered assemblies of nanowires are presented. We describe a convenient method to produce highly uniform and extremely thin ZnS nanorods and nanowires. Because of their uniformity, they spontaneously assemble into crystalline (nanorods), as well as parallel and crossed (nanowire) structures. Most importantly, we present an intimate view of the stages of nanorod-to-nanowire transition via a unique, oriented head-to-head attachment mechanism.