Nanowire network (NWNs) are comprised of random assemblies of individual wires coated with surface passivation layers that control global conduction.We show that the voltage and thickness dependence of conduction is controlled by the interwire junction properties.We develop a universal scaling relationship and demonstrate the presence of locally connected regions or cells that ultimately lead to global conduction1.Network connectivity is shown to evolve in response to an applied electric field to create materials whose conductivity can be arbitrarily controlled.We demonstrate the generality of these concepts by fabricating and testing memory devices and we discuss potential opportunities in the area of neuromorphic computing.