This document discusses intergenerational family systems, which are families with a biological parent living with an adult child. It has doubled since 1970. Assessing these families requires knowledge of aging beliefs and life course development, looking at how age, relationships, transitions, and social change shape lives. Impacts include cultural expectations, intergenerational relationships, and families evolving over time through normative transitions like children leaving home and non-normative ones like an elderly parent moving in. A life course perspective assesses family history, linked lives, and divergent paths over generational, individual, and historical time through principles of age stratification, cohorts, and trajectories.