As a powerful and efficient method for altering and controlling the properties and performance of materials, doping can enable properties that are innately present in a material. This book presents recent advances in the doping of organic electric materials and magnetism materials and reviews recent results also of doped naonocrystals and bulk materials. Doped bulk materials have been widely applied in many fields, such as optical display, communication, constructive materials, laser crystals, and biological systems. Doping has proven to be one of the most efficient techniques to adjust the electronic properties of organic semiconductors.