The eight stages of Erikson's psychosocial theory of development are: Infancy 0-18 months , Toddler/Early Childhood 18 months-3 years , Preschool/Play Age 3-6 years , School Age 6-12 years , Adolescence 12-18 years , Young Adulthood 18-35 years , Middle Adulthood 35-55 or 65 years , Late Adulthood 55 or 65 to death .