The purpose of this discussion paper is to explore ways the Australian Government can develop the social impact investing market. This discussion paper proposes that the Australian Government could primarily support social impact investing by creating an enabling environment for private sector social impact investors and by funding (or co-funding with State and Territory Governments) investments which generate savings or avoided future costs to fund reforms and deliver better outcomes for Australians. The paper starts off by providing an overview of social impact investing including the main forms of social impact investment and the benefits and challenges of social impact investing in Australia. It moves on to consider the roles of the Australian Government, investors and service providers, and possible policy areas of opportunity for social impact investing for the Australian Government. The paper then ventures into setting out principles to guide the Australian Government’s involvement in the social impact investing market before moving into a discussion on the possible regulatory barriers to the growth of the social impact investment market.