Stress may be defined as any negative effect or condition that a living organism may suffer. Abiotic stresses, such as salinity, drought, high and low temperatures, ozone, heavy metals, low concentration of nutrients in degraded soils, can cause deleterious effects in almost all phonological plant stages, from germination to full plant development. It has been estimated that 70% of the crop yield loss can be attributed to abiotic stresses, especially drought. It is known that plants respond readily when challenged by abiotic stresses by the modified regulation of many genes. This is a manifold response consisting of transcriptional and translational mechanisms that allow the adaptation of plants to many unfavorable environments. This book discusses the regulation of abiotic stress responses in plants; the structural aspects and functional regulation of late embryogenesis abundant genes and proteins conferring abiotic stress tolerance in plants; and dehydration responsive element binding transcription factors.