This course aims at providing students with an understanding of how life events experienced at an early time point shape behavior years later. It examines widely-held but scarcely tested assumptions of psychological theories on long-term effects on behavior, such as the effects of early development on adult life outcomes or changes in behavior from early to late adulthood. The course introduces existing long-term longitudinal studies, provides examples from popular hypotheses about long-term effects on behavior, surveys evidence on whether these hypotheses are supported and if yes, discusses which mechanisms are responsible for producing these long-term effects.