This book addresses how longitudinal research approaches are used to understand young people's lives. It elucidates how youth researchers use longitudinal approaches, and how longitudinal research can help us to both understand and shape the field of youth sociology. Chapters discuss the creation of knowledge about youth and how longitudinal research shapes the field of youth sociology and shed light on key tensions and emerging debates in longitudinal youth research ranging from research design to data collection, analysis, and use. It considers longitudinal studies using a broad range of methods, including qualitative, quantitative, mixed methods, retrospective methods, and creative and participatory methods. This collection offers insights from longitudinal youth scholars conducting research in Argentina, Lithuania, Australia, Estonia, Canada, the United States (US), the United Kingdom (UK), Finland and India. These researchers reflect on the future of longitudinal youth research, addressing emerging and prospective issues. This book provides a concise survey of key established and emerging areas of concern in longitudinal research and of the relationship between these areas and the field of youth studies more specifically.