Psychosocial development is a psychoanalytic theory proposed by psychologist Erik Erikson (1902–1994) that describes the impact of social interaction over a lifespan. Erikson proposed eight development stages that a healthy human should go through from infancy to late adulthood. In these stages, the person faces and attempts to overcome new challenges to go through the next stage. Because each stage builds upon the completion of previous stages, the failure to overcome challenges successfully may reappear as problems in the future.

Psychosocial development, as proposed by Erik Erikson, consists of eight stages of development: trust (birth to 12 months), autonomy (one to two years), initiative (three to five years), industry, identity (12 to 18 years), intimacy, generativity, and ego integrity (60s and above).

As a student of Anna Freud (1895–1982), Erikson was deeply influenced by Sigmund Freud's (1856– 1939) theory of psychosexual development, which contributed to the creation of Erikson's theory of psychosocial development. Specifically, the first four of Erikson's life stages correspond to Freud's oral, anal, phallic, and latency phases, respectively, while the fifth stage of adolescence parallels the genital stage in psychosexual development.

An important component of Erikson's psychosocial stage theory is the development of ego identity, which is the conscious sense of self that is formed through social experiences and interactions. Ego identities are constantly in flux as new information and experiences are acquired daily. In addition, Erikson believed that people are motivated by a competency. Through each stage, the person attempts to become competent in one area of life. If successful, he or she will feel a sense of fulfillment and contentment, which is also ego strength. However, if unsuccessful, he or she will feel inadequate.