The period marks a shift from universal stage accounts of adulthood to a lifespan perspective that foregrounds ongoing adaptation, resilience, and context-driven growth across the lifespan. Researchers emphasize midlife transitions, coping with diverse life demands, and the integration of cognitive and social-emotional development into a coherent model of maturity. Methodologically, cross-sequential designs begin to disentangle age, cohort, and time effects, revealing plasticity and variability in adult development within changing social contexts.