The 2010 INPES Health Barometer, on which this book is based, analyzed data from more than 6,000 young people aged 15 to 30. The strength of this representative sample lies in its ability to allow comparisons not only between young people and other age groups, but also among young people in different life situations. It offers a quantitative perspective on their health behaviors and provides insights into social health inequalities—an approach that has become essential for observing and understanding health behaviors. As illustrated by the analyses presented in this book, young people in disadvantaged social situations generally exhibit significantly worse health indicators than their peers. These data, which measure in particular the impact of actions undertaken by public authorities, make it possible to track developments and progress made since 2005, as well as the progress that remains to be made. They highlight the importance of the social and public health issues surrounding youth. The survey questionnaire is provided at the end of the book.