Semiconducting chalcogenides in various nanoforms have gained importance in recent years due to their size and shape dependent physical properties. Amongst them Cadmium Sulfide (CdS) has gained recognition as a promising material for light emitting diodes, solar cells and photoconductive devices by virtue of its photosensitive properties. So far, field emission studies on CdS nanostructures have been aimed towards the synthesis of various morphologies by a variety of routes, the attainment of lower turn on voltages, higher current densities at lower fields, and better stability. Present book deals with the literature survey in regards to the synthesis and field emission studies of CdS. Controlled synthesis of CdS nanostructures as well as their detailed optical, structural characterization and also field emission investigations are summarized in the book. Since CdS exhibits intrinsic photoconductivity, it is of scientific and technological interest to explore the photo-enhanced field emission behaviour of its nanostructures which is basic intend of the book. Possible reasons behind the observed photo-sensitive field emission behaviour are also discussed in detailed.