The rapid and formative rise in research on social innovation and entrepreneurship means that theoretical frameworks are still being created, while traditional notions of economic efficiency and social welfare are tested. The field is progressing fastest in the measurement and measuring of social entrepreneurial effectiveness. Social innovators, who draw from philanthropy, as well as capital markets, for financial resources, have adopted the lean start up as a paradigm for their organization logics. This collection showcases the myriad emerging philosophical, methodological, and...