The trend in electronics to reduce device dimensions well below the sub-micron scale inevitably leads to mesoscopic devices, i.e. devices that exhibit quantum effects. These effects certainly have to be taken into account and may even be exploited when developing more and more miniaturized electronic circuits. This book introduces very recent results of active research on such phenomena with an emphasis on single-electron tunneling (SET). Besides a balanced presentation of theoretical aspects and experimental results of single-electron tunneling intunnel junctions, junction arrays, and one-and two-dimensional electron gas systems, a rich collection of other quantum effects in mesoscopic devices and phenomena in semi-/ superconducting junctions are treated in detail. The purpose of this volume is to provide an up-to-date referencebook on the status of a field that is just emerging and promises a future ofexciting new physics, electronics and technology.