Erikson developed eight stages of psychosocial development across the lifespan: trust vs mistrust (infancy), autonomy vs shame and doubt (toddler), initiative vs guilt (preschool), industry vs inferiority (school age), identity vs role confusion (adolescence), intimacy vs isolation (young adulthood), generativity vs stagnation (middle adulthood), and integrity vs despair (late adulthood). At each stage, individuals face psychosocial crises that can result in healthy or unhealthy outcomes depending on how they are resolved. Erikson's theory emphasizes how social and cultural experiences shape personality development at each stage.