Chronological age: number of years since birth, legal (retirement/pension, genetic clocks. Generational cohort: experiences (world events, peer comparisons. Biological: growth vs decline, relative to life expectancy. Psychological: quantity/quality cognition, coping and adaptive capacities. Healthy successful" aging: maturity: growth completed, strength/skill: experience & expertise, knowledge: wisdom, independence: wealth, contribution to others: leadership. Lifespan development (baltes: multi-directionality: growth and decline, plasticity: learning and adaptation continues, historical context: time and culture of cohort, multiple causation: biological, psychological, socio-cultural and life-cycle forces, growth, maintenance, loss regulation. Forces of development: biological and physical: physical characteristics and genetic effects, psychological: cognition, perception, emotion, personality, socio-cultural: interpersonal, societal, cultural, ethnic, life-cycle: different effects of env factors depending on point in life. The contextual paradigm: adults influence and are influence by life contexts including, person-level factors, biological: health and physical skills, psychological: emotional/mental skills, environmental factors, physical environment, social/cultural/historical environments, interdisciplinary research approach and biocultural co-constructionism.