This review explores the state of the art in corporate social innovation (CSI) research. It briefly outlines the main themes in the corporate social responsibility debate and the organizational innovation literature  The paper then reviews the major objects of corporate social innovation singling out the base of the pyramid (BOP), social entrepreneurship, and eco-innovations as key themes. It closes by analyzing how social innovation is enacted at each of the four levels discussed in the first part. Finally, a list of references concerning real life practice is included to function as inspirational readings.