To measure its impact within the four public good impact themes through a program evaluation, as well as evaluate IDH impact at corporate level, IDH has requested Wageningen University & Research (WUR) & KPMG Advisory N.V. (further ‘KPMG’) to design and conduct a five-year impact evaluation program. This program is implemented between 2016 and 2020, and supervised by the IDH Impact Committee. This study is the first report of the impact evaluation program. In it, we provide a first synthesis of the available impact evidence for each impact theme as well as per result area. The synthesis combines information on IDH’s contribution to public good impact so far and information from the literature on the impact of and lessons learnt from similar approaches, to come to conclusions on the plausibility of IDH’s approach.