SIA first emerged in the 1970s in the U.S, as a way to assess the impacts on society of certain development schemes and projects before they go ahead - for example, new roads, industrial facilities, mines, dams, ports, airports, and other infrastructure projects. It has been incorporated since into the formal planning and approval processes in several countries, in order to categorise and assess how major developments may affect populations, groups, and settlements. SIA is often carried out as part of, or in addition to, Environmental Impact Assessment, but it has not yet been as widely adopted as EIA in formal planning systems, often playing a minor role in combined environmental and social assessments. http://en.wikipedia.org/wiki/Social_impact_assessment