Аннотация:This study examined the relationship between paternal alcoholism and toddler behavior problems from 18 to 36 months of age, as well as the potential moderating effects of 12-month infant–mother attachment security on this relationship. Children with alcoholic fathers had higher levels of internalizing and externalizing behavior than children of nonalcoholic fathers. Simple effects testing of an interaction effect of child age, group, and attachment security with mothers on externalizing behavior suggested that at 24 and 36 months of age mother–infant attachment security moderated the relationship between alcohol group status and externalizing behavior. Namely, within the alcohol group, those children with secure relationships with their mothers had significantly lower externalizing than insecure children of alcoholics. A similar pattern was noted for internalizing behavior at 36 months of age. Implications for intervention are discussed.The authors thank the parents and infants who participated in this study and the research staff who were responsible for conducting numerous assessments with these families. This study was made possible by grants from NIAAA (1RO1 AA-10042-01A1) and NIDA (1K21DA00231-01A1).