This book brings together two leading researchers in the field to provide a comprehensive overview of the shadow economy from a global perspective. Reviewing the advantages and disadvantages of different ways of measuring the informal sector, the authors evaluate its size and key determinants across the world. Williams and Schneider clearly establish the persistence and prevalence of the shadow economy, analysing the narrowness of existing policy approaches and explaining how these fail to address the key factors for its existence and may even exacerbate the problem.