The 1982 Pelotas Birth Cohort is the first of four large population-based cohorts based within the Brazilian city of Pelotas. Following the success of the current cohort in 1982, the development of a new cohort began every 11 years (1993, 2004, and 2015). All births that occurred during the whole of 1982 were identified. Of these, 5,914 live born infants constitute the original cohort. A random sub-sample of 360 four-year-old's was also selected for an in-depth study of psychomotor development. Follow-up visits of the main cohort have been carried at the mean ages of 1, 2, 4, 13, 15, 18, 19, 23, and 30 years. Most visits included subsamples of the cohort, except for those at 2, 4 and 23 years.