This study aims to identify substance use patterns in a community sample of pregnant women and their partners during the prenatal period and the characteristics associated with substance use. Next the study aims to examine the relationship of maternal and paternal substance use with pregnancy outcomes for mothers and their infants. Finally, the study aims to determine the extent to which substance use in pregnant women and their partners predict problems in (a) infant development (physical, cognitive, behavioural and emotional), and (b) family functioning (marital/intimate partner relationship quality, conflict and violence, parenting behaviour and parent-infant relationship quality).