This report focuses on the general suitability of Impact Assessment (IA) when applied to social innovations. The main question is: How suitable is the IA approach (see Appendix for example and description of TNO IA approach), if it is applied to assess the impacts of social innovations with regard to policy changes? In order to answer the aforementioned question, the possibilities and challenges of IA for social innovation were explored by applying the IA method on three social innovation cases: local energy production, workplace innovation and car sharing. We developed a special format with questions for researchers to describe social innovation cases and relevant policy options. Cases described in this format are used to construct models, which can form the basis for IA calculations. In the first part we present the format (used to describe cases and related policies) that we have developed for IA of social innovation. The format consists of a questionnaire and tackles all aspects of social innovation and relevant aspects of policies that have impact on social innovation. In our second part, the three cases are discussed and presented. The local energy case shows how with governmental support energy production can be relocated from standard electricity producers to local centres. The workplace innovation case focuses on how coworking spaces were co-initiated by public and private entities. The car sharing example shows how municipalities can ease and facilitate the process of car sharing. Three different models were created for all cases: 1) general, 2) simplified general, and 3) models with regard to different stakeholders. Hereafter, we shortly formulate the findings that increased the understanding of IA of social innovation. It was acknowledged that it should be clearly defined whether the main focus is on policy impact on social innovation or social innovation on various stakeholders (society, environment, etc.). A new assessment approach was suggested: IA models can be developed for different stakeholders separately; in this way models can become less complex and, therefore, more applicable as a basis for (mathematical) computations of IA. However, there are some incongruences that arise from different theoretical aspects of IA and social innovation (e.g., different assumptions about institutional context, contextualization vs. general approach); those disagreements have to be taken into account before applying IA on social innovations. Finally, we suggest future actions for the actual execution and approach of an IA on a social innovation case and discuss future possibilities and difficulties that may arise applying IA on SI cases. In conclusion, IA can indeed be applied on social innovations, but additional considerations, as described in our report, should be taken into account. Moreover, our developed IA format for social innovation cases and the example case descriptions can help to facilitate this process.