The social impact assessment is an activity of social research and an assessment practice that has received an increasing spread. Burgeoned from the environmental impact assessment method, its early formulations aim to anticipate and mitigate the adverse social impacts of a proposed intervention, whilst also contributing to strengthening positive ones. Since the first applications, different versions of social impact assessment have been proposed, depending on the unit of analysis and the purposes of the evaluation. The article offers two reading tracks: the social impact assessments applied to programs, policies and reforms; and impact assessments applied to social enterprises and social investments. The article concludes with some notes on the contribution of social impact assessment to make a step further to reach the most relevant evaluation purposes and some cautions to consider in the development of these methods.