Our paper describes the results of a Social Return on Investment (SROI)analysis of four new housing projects in Germany. A common characteristic of all projects is the central importance of mutual neighborly support to meet the demand for assistance of older residents. All projects share some common architectural features and infrastructural characteristics. Furthermore, in each housing project some form of support by social workers takes place. Using a propensity score matching approach, we compare for the first time systematically the costs for support of older people in mutual support based housing projects with a control group of people living in conventional settings. Our results, based on a sample of more than 700 residents, point not only to improvements in living satisfaction, but indicate also a huge potential for socio-economic cost savings. This can partly be explained by better development of residentsí health status.