This book is intended to be a useful tool for academia and researchers interested in the chemistry and applications of organic chromophores with nonlinear optical properties (NLO). This book aims to review the various types of organic chromophores reported in literature with NLO properties, such as alkynes, tetraenes, azo dyes, chalcones, heterocyclic compounds, fullerenes, perylenes, ferrocenes and polymers, their structural features, properties and their nonlinear optics. parameters. 380 chromophores with NLO properties are presented in this book. The various applications of organic NLO chromophores, in medicine as luminescent materials, molecular switches, laser technology, spectroscopic and electrochemical sensors, microfabrication and imaging, data storage, optical signal modulation, telecommunications, make this field highly sought after and explored by researchers in the last decade.