An existing large-scale prospective birth cohort – the Boston Birth Cohort (BBC) – is transformed into an ASD cohort to efficiently and immediately investigate preconception, pre- and peri-natal risk factors and health services patterns for ASD. The BBC is a well-established and ongoing prospective birth cohort of a U.S. urban predominantly low-income minority population, now consisting of over 8,500 mother-infant pairs. The goal is to examine the independent and combined effects of maternal demographics, medical, psychosocial, home and neighborhood environments at critical developmental windows (preconception, pre- and perinatal) on the risk of ASD and Developmental Disabilities (DD), and to analyze health services patterns in this cohort.