The Yearbook of Paediatric Endocrinology counts years from June to June, when we submit the manuscripts to our publisher, and so much happened since June 2017. Our 13 Associate Editors and their coauthors do not take anything for granted and have once again done an enormous work to discern this year's advances. You will see that we cite papers on genomics and genetics, molecular biology and systems biology, evolutionary biology, clinical trials and medical reports to provide new insights in paediatric endocrinology, as the complexity of our field increases. Among other highlights, the Yearbook 2018 describes: new treatments (MC4R agonist for monogenic obesity; long-term outcomes of rhGH in chronic inflammatory disease; FGF23 antibody in children with XLH; oral GnRH antagonist), new genes (the CLCN2 chloride channel in primary hyperaldosteronism; genetic heterogeneity in T1DM; and new genes in severe obesity and hypogonadotrophic hypogonadism), new mechanisms (Stella insufficiency in oocytes induced by maternal obesity; noncanonical thyroid hormone receptor signalling; epigenetic control of puberty; hypothalamic stem cells control ageing speed; estrogen receptors and excess autoimmune disease in women) and other findings with important implications (consensus definition of fetal growth restriction in newborns; remission of childhood overweight on the risk of T2DM; the 'nocebo' effect; how your Pediatric Department can support Global Health). A growing number of included papers describe non-genetic inheritance (NGI). Transgenerational epigenetic inheritance is the form of NGI that has gained eminence: germline transmission of DNA methylation patterns, histone modification and small RNAs trigger the inheritance of traits, including child growth, puberty and development. But according to a new book by Russell Bonduriansky and Troy Day Extended Heredity: A New Understanding of Inheritance and Evolution (Princeton University Press), "Epigenetic inheritance is only the tip of the NGI iceberg." NGI also includes adaptive parental effects, social learning, the inherited microbiome, and structural inheritance in single-celled eukaryotes in predicting adaptive responses. In this Preface, we annually highlight a prize given in the field of endocrinology. Time and again, metabolic regulation attracts the highest accolades, and we salute Jeffrey Hall, Michael Rosbash, and Michael Young, recipients of the 2017 Nobel Prize for Physiology or Medicine, for their discoveries of molecular mechanisms controlling the biological clock. We also mark each year important science anniversaries: in 1918, L. Greving described the nervous connections between the hypothalamus and pituitary gland-a central dogma of endocrinology. Greving then discovered the tract of unmyelinated nerve fibers running down the neural stalk into the posterior pituitary. But 1918 was also the year of the Spanish flu, killing 50 million people, and World War I ended. Ninety-nine years later it was shown that these hardships in childhood were associated with worse ph...