Book excerpt: This book overviews the applications of viral nanoparticles (VNPs) in areas ranging from materials science to biomedicine. It summarizes the many different VNP building blocks and describes chemistries that allow one to attach, entrap, or display functionalities on VNPs. The book outlines the strategies for the construction of 1-, 2-, and 3-D arrays, highlights the achievements in utilizing VNPs as tools for novel biosensors and nanoelectronic devices, and describes efforts in designing VNPs for biomedical applications, including their use as gene delivery vectors, novel vaccines, imaging modalities, and applications in targeted therapeutics.