Certification of agricultural products (organic certification, Fairtrade etc.) is often expected to provide a wide array of benefits for small-scale farmers. These include poverty alleviation, reduced environmental impact and food safety. Together with Wageningen Economic Research we reviewed 270 studies and present an analysis of the benefits – but also the costs – of such schemes. It demonstrates that the decision to invest must be based on sound economic principles, and the text also provides recommendations to improve the certification business case and impact on smallholders.