Context: No epidemiological data are available on central precocious puberty (CPP) in the general population or in adopted or immigrant children in Spain. Objective: We aimed to study the incidence and prevalence of CPP, assess the risk of developing this disorder among adopted and immigrant children, and analyze the predictive variables of CPP associated with intracranial pathology. Design, Settings, and Patients: An observational study of children diagnosed with CPP in Spain was carried out between January 2008 and January 2010.Acomputer program was designed to process clinical and biological data and information on 250 patients treated in 34 pediatric endocrinology units throughout the country. Results: Of the patients registered, 226 were girls and 24 were boys. The global incidence rate of CPP was 5.66 cases per million person-years at risk, with an annual incidence ranging between 0.02 and 1.07 new cases per 100,000. The relative risk of CPP in domestic and internationally adopted children compared with those born in Spain was 27.82 (19.99 -38.77), whereas the relative risk among immigrants was 1.55 (0.97-2.38). A logistic regression model developed for the study showed that the combined effect of four variables had a significant influence over the presence of organic disease: being male, having been adopted, age at diagnosis, and estimation of adult height. Conclusions: CPP is a rare disease whose risk markedly increases with both national and international adoption but is not influenced by immigration. These results suggest a psychological influence on CPP. Copyright © 2010 by The Endocrine Society.