Intérieures Publiques (MRIP). It provides an overview of core issues in thinking about and advising on tax-based approaches to environmental problems in developing countries. The aim is to bring a rigorous and practicable public finance perspective to the environmental challenges faced by developing countries, with a focus on those over which they have some control. Special attention is paid to nineteen ‘priority countries,’ mainly Francophone and all but one in sub-Sharan Africa. The hope and intent, of course, is that the discussion and analysis have wider application and interest beyond these countries.