In its broad definition, social impact aims at measuring the consequences of a human activity in the context in which it is designed, developed, and implemented. The origin of the concept may be dated back to the end of the 1960s, when some agencies and organizations started to analyze the consequences that large scale interventions, like main infrastructures or plants, had or might have on the equilibrium of the environment. In terms of the work of nonprofit organizations, social impact is a relatively new concept, descending from the fact that, over the last decades, its definition moved toward a concept regarding the search for tools for planning projects and evaluating initiatives and actions which have important positive impacts on people’s lives, communities, countries, or society in general. Therefore today social impact deals with the definition of tools and instruments for demonstrating and accounting the impact of social programs and projects developed by nonprofit organizations with respect to their institutional social mission and mission-related goals. Nowadays the real challenge regarding social impact is the search, by nonprofit organizations, for valid tools and techniques for social impact assessment, measurement, and communication, both at an ex ante level in planning new projects, initiatives, and so on and at an ex post level, when it is necessary to demonstrate and “account” that the socially responsible planned action has given the expected results in terms of positive impacts upon the target and/or in general on people’s well-being.