In Vietnam beside economic values, small hydropower plants caused various adverse impacts on the natural environmental (change in hydrological regimes, shortage in water at downstream; erosion; deforestation; damage of biodiversity and biological resources); social conditions and environmental risks. The water regulation of small hydropower plants may significantly contribute in the serious consequences of flooding in the Central Region in months of October, 2020. However, so far, environmental and social impacts and management of this type of energy projects are not properly concerned in project appraisal and management. Therefore, to improve this issue the following best “Environmental and Social Guidelines for Small Hydroelectric Projects, prepared by: Le Trinh (Assoc. Prof. Dr. Env. Sci., Consulting Team Leader, Chief Editor), Vu Ngoc Long (Dr. Ecol. Sci., Tran Quy Suu (MSc., Social Specialist, ADB), Le Quang Huy (MSc., Hydropower Specialist) for Ministry of Industry and Trade (MoIT) in November 2016 under REDP (SECO TF098460) are introduced to be applied.