The negative effects of parental substance use on child well-being are well documented; however, little is known about the cumulative effects of parental prenatal and postnatal substance use on child maltreatment frequency and on foster care placement transitions. In this study, a cumulative measure of parental prenatal and postnatal substance use was employed as an indicator of child maltreatment frequency and foster care placement transitions. The cumulative measure of parental substance use predicted the global child maltreatment frequency and the number of foster care placement transitions. Multivariate and univariate analyses were conducted to examine the individual and collective roles of mother’s and father’s substance use on child maltreatment type and in the number of foster care placement transitions. Results indicated that father’s postnatal substance use predicted the frequency of physical abuse and the frequency of neglectful «failure to provide.» The combination of mother’s prenatal substance use and mother’s postnatal substance use predicted the frequency of neglectful failure to provide. The combination of mother’s and father’s postnatal substance use predicted the frequency of child sexual abuse and the number of foster care placement transitions. Implications and directions for future research based on these findings are discussed.