AbstractIt was in 1946 that Great Britain embarked on the world’s first ever large-scale child cohort study, designed to track participants from birth to adulthood. Half a century on, this study is still going strong and has been extended to include the second generation, namely children born to the members of the original cohort. The past fifty years have witnessed the launch of many similar initiatives worldwide, as this type of longitudinal study allows researchers to adopt a dynamic approach to child development and gain a clearer understanding of children’s long-term trajectories. This article describes the experience gained from a series of major multidisciplinary child cohort studies. It highlights the wide diversity of their themes (children’s health is the common denominator) and sampling methods (some cohort studies rely on existing statistical sources), as well as variations in the interval between each successive wave and the duration of follow-up, survey tools (which sometimes include biological sampling), the types of family tracking methods employed and their respective success rates. Precise data on attrition are provided for some of the studies, together with examples of scientific findings. The appendix contains detailed information about the methodology, objectives, strengths and weaknesses, institutional support and funding of twenty large-scale child cohort studies.