Certification of agricultural products is an increasingly common tool that is expected to contribute to agricultural improvement, farmer well-being, poverty alleviation, reduced environmental impact and food safety. In an increasingly competitive market, processors, manufacturers and retailers use certification to demonstrate their green and sustainable credentials and differentiate their products. In some commodity sectors, such as coffee and cocoa, products certified as sustainable are on track to reach majority market share in important producing and consuming nations. This development poses a major challenge for farmers in general, and small-scale farmers in ACP and other developing countries, in particular. This publication, commissioned by CTA, presents the findings of a study of the impact of certification on farmers in coffee, cocoa, cotton, fruit and vegetables.