The prediction of conduct problems (CPs) from infant difficulty and parenting measured in the first 6 months of life was studied in a sample of 267 high-risk mother–child dyads. Stable, cross-situational CPs at school entry (5–6 years) were predicted by negative infancy parenting, mediated by mutually angry and hostile mother–toddler interactions at 24–42 months. Mother–child interactions late in toddlerhood were especially relevant for CPs. Contrary to predictions, difficult child behavior in the first 6 months of life was not consistently associated with CPs, either independently or in interaction with negative infancy parenting. The findings most strongly highlight the role of negative mothering in early infancy, and of changes in mother–toddler interaction, in early onset CPs.