This publication presents some of the most comprehensive information currently available on the origin and structural characteristics of the immigrant population in OECD countries. It includes a large set of tables and charts describing demographic characteristics (age, gender, duration of stay) and labour market outcomes (labour market status, occupation, sector of activity) of immigrant and native-born populations by educational level and country of birth. These are covered in nine thematic chapters, each including a brief description of sources, a discussion of cross-country differences as well as a short analysis of a specific issue, such as the gender dimension of the brain drain, the international migration of health professionals, or the role of low-skilled foreign-born workers in domestic services. The data are taken from the new OECD Database on Immigrants in OECD Countries (DIOC), which compiles information gathered from the last round of censuses. They are being published here for the first time.An introductory chapter provides an overview of the data available and presents a picture of international migration to the OECD area from four regions, namely Africa, Asia, Latin America and OECD countries themselves. The chapter also focuses on a number of specific topics, such as the feminisation of migration, the role of high-skilled migration and the intra-OECD mobility of human resources, This book is essential reading for experts and policy makers. It paves the way for further research and policy analysis of a range of issues around international migration which are of high priority for many OECD countries.