This book discusses the molecular, physiological, and metabolic aspects of GABA in enhancing stress tolerance in plants by scavenging reactive oxygen species (ROS). It contains updated information on the effects of GABA on stress tolerance systems and their control in improving crop performance. This book also discusses the regulatory role of GABA under stressful environments in plant systems, which has previously been overlooked in crops under abiotic and biotic stress conditions. The generation and elimination of ROS in plants are balanced under normal conditions, but abiotic environmental stress responses disrupt this equilibrium by increasing the generation of ROS or free radicals. GABA is a molecule of interest among stress-responsive metabolites and it involves nitrogen assimilation in amino acids during plant growth and leaf senescence process. The high accumulation of GABA acts as an osmo-protectant during oxidative and osmotic stress conditions and can lead to ameliorative synthesis in cells and reducing their degradation. Further, GABA has a quenching ability on ROS production in plants during various environmental stress conditions. This book benefits the researchers, scientists, students, innovators, and academicians, working to understand the role of GABA molecule to impart abiotic stress tolerance.