The present Comprehensive report encloses a review of the state of art regarding social impact measurement and best practices in each partner country, namely Croatia, Italy, Cyprus, Norway, Israel, Portugal, Poland and Greece. This report marks the culmination of a feedback process undertaken in each of the countries represented in SIM4CSOs project. Impact measurement provides critical organizational infrastructure, serves as a sense-check for service delivery, a way to attract and communicate with donors, and more. Yet, despite their motivation and intentions, many CSOs do not currently have the financial and technical resources to carry out a full process of impact measurement and evaluation. However, overall, a need to share measurement approaches was expressed. Questionnaires and focus groups allowed project partners to gain a deeper understanding of the practitioners’ needs and interests in the field, which will guide the development of a tailored toolkit with step-by-step guidance on how to implement effective social impact measurement.