Abstract: The German Health Interview and Examination Survey for Children and Adolescents (KiGGS) provides comprehensive and reliable data on the health situation of the upcoming generation. The KiGGS cohort accompanies participants from the KiGGS baseline study (2003–2006) into adulthood. Until now, two follow-up surveys of the cohort have been implemented with KiGGS Wave 1 (2009–2012) and KiGGS Wave 2 (2014–2017). In KiGGS Wave 2, the cohort was supplemented by the in-depth study ‘Family and care-specific factors influencing the development, trajectories and effects of mental disorders (especially ADHD), obesity and allergic diseases (especially asthma)’. One aim of the study was to identify individual trajectories of these health disorders. For this purpose, probabilities for typical transitions from the KiGGS baseline study to KiGGS Wave 2 were calculated. An important result is that many participants who had asthma, obesity or ADHD at KiGGS baseline still had the disease more than ten years later: Over a third still had asthma (35%) or ADHD (37%), and almost half were still affected by obesity (47%). The results point to the need for early preventive measures to stop these potentially chronic diseases from developing in childhood and adolescence.