The International Childhood Cancer Cohort Consortium (14C) is an alliance of several large-scale prospective cohort studies of children to pool data and biospecimen from individual cohorts to study various modifiable and genetic factors in relation to cancer risk. This initiative brings together international multidisciplinary teams of epidemiologists, basic scientists, and clinicians, to collaborate on investigations into the role of early-life exposures on cancer risk. This international alliance of longitudinal studies of children has the potential to make major contributions in advancing understanding of the role of early-life exposures in childhood cancers and other diseases.