This book is the first publication to provide a comprehensive overview about the market, financial instruments and the associated impact assessment for interested practitioners and academics. Specifically, it will introduce the concept of impact investing within the broader field of social finance as well as the relevant actors, present current financing instruments and the various tools to assess the impact of the investing strategy. This useful reference tool will be of interest to academics and researchers in the field of impact investing. Impact investing is a dynamic field that has been recently been discussed as a supplemental funding source for addressing societal problems. The topic has generated significant interest and is presumed to achieve double-digit growth rates for the coming years.