The relationship between maternal parenting stress and infant/toddler behavioural development was examined in a longitudinal pilot study. Fifty mothers reported parenting stress via the Parenting Stress Index-Short Form when their infants were eight months old. Parents subsequently rated their children's emotional and behavioural problems with the Child Behaviour Checklist at both 18 and 36 months of age. Preliminary results suggest that mothers reporting higher stress levels in their infant's first eight months also reported greater emotional and behavioural problems in their children at 18-and 36-month follow-up assessment. Parent report of children's total and externalising problematic behaviours decreased over time, regardless of the maternal stress level. In contrast, parent report of internalising problem behaviours remained stable over time; however, at both 18-and 36-month follow-up assessments, high-stress mothers reported higher levels of internalising problems in their children than did low-stress mothers.