The definitive work on the best ways to support the healthy development of children and adolescents and their families, based on 20 years of the groundbreaking TOPP Study The unique longitudinal study "Tracking Opportunities and Problems (TOPP)" began following nearly 1,000 children and their families in Norway in 1993. Few studies have ever accumulated such extensive information from such a large number of families. Eight waves of data on many aspects of child and family life have been collected from children aged 18 months to 18 years. The TOPP Study has provided new knowledge about and insight into the precursors, developmental paths and predictors of both good adaptation and mental health problems of children, as well as into parenting and family relationships. The editors have collated the key findings in three parts. Part 1 addresses the mental health and development of children and adolescents. Part 2 focuses on parents, looking at individual parental and family-related factors, including parental couple relationships. Part 3 looks at the methodological issues, including the sample, response rate and measurement and analytical approaches. Each chapter reviews the existing knowledge in these areas in relation to the TOPP findings and provides extensive reference lists for those who want to dig deeper. This unique book provides thought-provoking insights into the TOPP findings to help guide therapeutic practice, to suggest new avenues of research, to inform teaching, and to shape policy planning and preventive actions. It is thus an invaluable resource for all professionals, researchers, educators, policy makers, and students working with children and adolescents and their families.