Nonlinear optics has been a rapidly growing scientific field in the recent decades. It is the study of the interactions of light with matter under the condition in which the nonlinear response of the atoms plays an important role. This book clearly explains the basic requirements needed for the nonlinear optical materials. The general level of presentation has been kept elementary with emphasis on the physical reasoning underlying the interpretation of the nonlinear optical materials suitable for device fabrications. Nonlinear optical (NLO) materials find useful applications in the fields of photonics and optoelectronics. This book presents fundamental aspects of growth and characterization of some NLO materials Trisglycine Zinc Chloride (TGZC), Triglycine Acetate (TGAc), Glycine Lithium Sulphate (GLS), L-Prolinium Tartrate (LPT) and Dichloridodiglycine Zinc Dihydrate having more SHG efficiency. The grown materials using solution growth technique are subjected to XRD, FTIR, UV, Dielectric, Hardness, Thermal, Electrical and Photoconductivity studies to confirm the characteristics required for the NLO activity of the materials.