Cleaved Edge Overgrowth is employed to fabricate atomically precise single and coupled quantum wires. Single wires were investigated in the diffusive and ballistic transport regimes. In addition to a detailed understanding of the 1D sublevel structure in the complex CEO devices, clear indications of Luttinger liquid behavior of the one-dimensional electron systems were obtained. Coupled quantum wires were studied in the two limits of large and small separations. In the first case shallow ID potentials were chosen and an alternative description for commensurability oscillations in weakly modulated two-dimensional electron systems could be derived. For the coupled quantum wires with small separations and a large potential modulation the validity of the miniband transport picture leading to negative differential conductivity was demonstrated. (c) 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.