Despite the centrality of impact measurement in the Venture Philanthropy approach and of the large uptake of the five-step program, many venture philanthropy organizations still consider it difficult to implement impact measurement in their daily practice, and ask for more guidance as of the do’s and don’ts of impact measurement. The two case studies presented in this report aim to fill this knowledge gap, by providing examples of how two leading organisations – Investisseurs et Partenaires (I&P) and Reach for Change – have developed their own impact measurement system and how they have dealt with issues such as proportionality, attribution and additionality.