The Centre for Social Investment (CSI) is a research centre at the Max-Weber-Institute for Sociology in the Faculty of Economics and Social Sciences of Heidelberg University. It sees itself as an interdisciplinary centre in research, education and training as well as a transdisciplinary partner for the third sector. The central research topics of the CSI are, in addition to the eponymous social investments and innovations, foundations, civil society and the social economy. Special attention is paid to innovative cross-border research - be it between sectors or between forms of organizations. From a comparative or often exploratory perspective, research projects are carried out at national, European and international levels. The CSI's research contributes to fundamental theoretical understanding, applied knowledge and political and strategic debates in civil society and the third sector, thus defining this area alongside the market and the state. CSI research aims to contribute to the shaping of self-perceptions of the third sector, to analyze its legal, economic and social framework conditions, and to contribute to increasing the effectiveness of social enterprises. Our research results are communicated to the public not only through teaching and professional qualification mechanisms and publications, but also put into practice through cross-sector transdiciplinary formats of cooperation on social innovation formats, e.g. in innovation laboratories.