This book, in addition to giving the readership the role of diamondoids as molecular building blocks in nanotechnology, it gives the readership an excellent background science and technology about molecular structure, physics and chemistry of diamondoids, the role and nature of diamondoids in fossil fuels, physical properties of diamondoids, properties of diamondoids, and biomedical and materials science applications of diamondoids. Interestingly, it is shown in this book that ab initio calculations are quite useful for molecular property prediction of diamondoids and their derivatives, especially for the fact that there exist a huge number of such molecules. The book also gives an excellent description of quantum confinement effects and negative electron affinities of diamondoids which are their unique characteristics. The first-principles simulations of interaction of diamondoids with other systems such as carbon nanotubes, metallic surfaces, and metallic AFM cantilever tips, which are the promising ways to design new nanomaterials are well presented in this book. Additionally, functionalized diamondoids which have led to the creation of nanosystems with new chemical and physical properties and with suitable applications in pharmacology and electronic devices are also presented very well in this book.