For the past 40 years, investigators at Harvard Medical School, the Harvard School of Public Health and Brown University have conducted and maintained a three-generation longitudinal study of 17,000 persons from the NCPP cohort, followed from before birth through age 40. The NEFS is directed by Dr. Stephen Buka; projects based at MMHC are co-directed by Drs. Jill M. Goldstein, Larry J. Seidman and Ming T. Tsuang.

Initial study enrollment of the NCPP occurred between 1959-1966, during the first prenatal visit of pregnant women. At the time of registration for prenatal care, data from examinations and interviews were recorded by trained staff using standardized protocols, forms, manuals and codes. Prenatal clinic visits were scheduled every month during the first 7 months of pregnancy, every 2 weeks during the 8th month, and every week thereafter. Data on neonatal progress were recorded by pediatricians and nurses.

After the neonatal stage, the child was seen at five subsequent assessments during childhood: ages 4 months, 8 months, 12 months, 4 years and 7 years. Follow-up visits included pediatric, neurological and psychological assessment of the child and maternal interviews. Follow-up rates for the New England cohort surpassed the national project rates; over 80% of the New England cohort completed the final full assessment at age 7.