The properties of nanoscale materials are derived from the additional dimensional and compositional degrees of freedom that arise when the physical dimensions of the system are smaller than a characteristic length scale of interest. Anisotropic particles can exhibit novel and enhanced properties compared to isotropic spherical particles. This book focuses on all aspects of anisotropy on the nanoscale. In addition to the synthesis of new anisotropic materials, the ability to address individual nanostructures is important for technological applications such as nanoelectronics and biomedical engineering. Furthermore, the assembly of ordered 1-D, 2-D, and 3-D arrays of anisotropic nanoparticles presents challenges not encountered with isotropic particles. Chemical interactions and electric fields can be used to assemble ordered arrays from colloidal suspensions. The ability to address isolated anisotropic particles allows fundamental measurements of properties. By assembling an extremely multi-disciplinary group of scientists, this book attempts to address all of these issues. Topics include: metallic nanoparticles and clusters; metallic nanowires; nanowires and nanotubes; nanoparticles in biology; and semiconductor nanoparticles.