Outline: Characteristics of informal businesses in West Africa -- Institutional, regulatory and socio-cultural environment -- Costs and benefits of informality: productivity, living standards, and tax revenue -- Main conclusions and recommendations -- Chapter 1. The informal sector in West Africa: definition -- Chapter 2. Data sources and methods -- Chapter 3. The informal sector in west Africa: overview of economic significance and welfare effects -- Chapter 4. Large informal firms in West Africa -- Chapter 5. Characteristics of the informal sector: findings from our surveys -- Chapter 6. The institutional environment of the informal sector in West Africa -- Chapter 7. Informality and productivity -- Chapter 8. Informal trading networks in West Africa: the Mourides of Senegal/Gambia and the Yoruba of Benin/Nigeria -- Chapter 9. Government policies, smuggling and the informal sector