Temperament dimensions influence children's approach to and participation in social interactive experiences which reflect and impact children's social understandings. Therefore, temperament differences might substantially impact theory-of-mind development in early childhood. Using longitudinal data, we report that certain early temperament characteristics (at age 3)--lack of aggressiveness, a shy-withdrawn stance to social interaction, and social-perceptual sensitivity--predict children's more advanced theory-of-mind understanding 2 years later. The findings contribute to our understanding of how theory of mind develops in the formative preschool period; they may also inform debates as to the evolutionary origins of theory of mind.