This book discusses functionalization methods for conjugated polymers, designed to confer features including optical and electronic properties, recognition, self-assembly, and compatibility with biological and living systems. Its focus is on functionalizing organic semiconductors as a means for tailoring their properties and creating new materials with surprising features and performances. The book features 16 chapters organized in four sections: fundamentals, applications in organic optoelectronics (especially photovoltaics, electroluminescence, nonlinear optics), functionalization for recognition (with a special emphasis on chemo- and biosensing), and functionalization for generation of supramolecular architectures and hybrid systems. The result is a unified presentation of the state-of-the-art in functionalized conjugated materials with a view on future developments in organic optoelectronics and biology.