This Report of the Strategic Social and Environmental Assessment (SSEA) - which is the first part of the JMP Phase -1 Identification Phase - consists of a Main Report ((Volume 1) and a Baseline Report; (Volume 2). The SSEA aims to provide an inclusive and participatory assessment of the environmental and social issues associated with various development options for cooperative water resource development in the Abbay/Blue Nile and Main Nile sub-basins. It is meant to support informed and transparent decision-making in the identification and selection of investments for water resources development. The SSEA compares water resources development alternatives comprising a range of investments - from a no-investment to a full cooperative development of the water resources of the sub-basin - in infrastructure for hydropower generation and multipurpose uses (flood control, irrigation and drought alleviation). It examines connections and impacts of potential development scenarios on the physical, biological, socio-economic, and cultural resources of the region and determines thresholds and tipping points where the impacts, positive or negative, start to be felt basin-wide.