["Infant Mental Health Journal: Infancy and Early Childhood, Volume 47, Issue 3, May 2026. ", "\nAbstract\nEarly childhood is a sensitive period when stress exposures may be particularly influential for socioemotional development. The current study examined the impact of maternal perceived stress at multiple longitudinal time points during the first year of life on child psychopathology symptoms at 2 years. Participants in the current study (N = 211) were part of a longitudinal prospective cohort that was followed during early childhood. Maternal perceived stress was assessed using the Perceived Stress Scale (PSS) at 2, 6, 9, and 12 months. Child socioemotional characteristics were assessed at 2 years using the Infant‐Toddler Social and Emotional Assessment (ITSEA). Structural equation models (SEMs) were used for statistical analyses. Higher maternal perceived stress at 9 months was associated with more general anxiety (internalizing), sensory sensitivity (dysregulation), and post‐traumatic stress (dysregulation) symptoms. Higher maternal perceived stress at 12 months was associated with more separation distress (internalizing) and negative emotionality (dysregulation) symptoms. Maternal stress was not significantly associated with any symptoms within the externalizing domain. These findings suggest that the latter half of the first year of life (9 and 12 months) may be a sensitive period for stress exposures, and interventions reducing caregiver stress during this window may also improve socioemotional development transdiagnostically.\n"]