Abstract
Materials with desirable properties may be created through control of crystal size and shape and assembly of such crystals into more complex arrangements. In his Perspective, Heath discusses recent work reported in this issue by Murray et al . ([p. 1335][1]) in which nanocrystals of cadmium selenide were formed into ordered assemblies of quantum dots. Such results represent a first step toward self-assembly of device structures. [1]: /lookup/doi/10.1126/science.270.5240.1335