Parenting stress disrupts both parenting and child adjustment. Marital intimacy is often conceptualized as a source of support that may reduce parenting stress. We examined the association between mothers' trajectories of parenting stress and marital intimacy when their children were 15–36 month old. We also explored whether maternal depressive symptoms at 15 months accounted for individual differences concurrently or in the trajectories of parenting stress and marital intimacy. Mothers' marital intimacy was negatively associated with their concurrent levels of parenting stress and declines in parenting stress over time. Depressive symptoms were associated with 15‐month parenting stress and marital intimacy. Overall, intimacy within the marriage appears to be a resource that reduces mothers' parenting stress during the toddler years