This chapter describes the use of DNA for molecular-scale self-assembly. DNA nanostructures provide a versatile toolbox with which to organize nanoscale materials. The chapter commences with a discussion of DNA nanostructures, the self-assembly of various building-blocks known as DNA tiles, and how these can be made to self-assemble into two and three-dimensional lattices. Methods are then discussed for the programmed assembly of patterned and/or shaped twoand three-dimensional DNA-nanostructures, including their use to produce beautiful algorithmic assemblies displaying fractal design patterns. The resulting large DNA nanostructures provide multiple attachment sites within and between tiles for complex programmed structures, which leads to diverse possibilities for scaffolding useful constructs and templating interesting chemistries. Methods are then described for the assembly of various biomolecules and metallic nanoparticles (NPs) onto DNA nanostructures, and also of various materials using DNA nanostructures. The chapter is concluded with a discussion of the various challenges faced by DNA nanostructure self-assembly.