The spread of impact investments from a niche field into the mainstream financial market raises new demands on impact measurement. Instead of evaluating single interventions, impact investors increasingly aim at rating large portfolios of enterprises based on comprehensive impact considerations. Thus, it is necessary to scale impact measurement and enable a large-scale quantitative and data-based impact assessment. Therefore, this paper transfers the synthetic control method, developed by Abadie & Gardeazabal (2003), into the field of impact investing, by evaluating the prerequisites for its implementation as well as discussing possible applications to a large universe of companies and a broad range of asset classes. This approach might represent a first step in developing a measurement framework for a large impact investing market, applicable in research as well as in practice.