- life cycle: uses emotional and intellectual stages from childhood-retirement
- developmental task: uses growth responsibilities that arise at different stages in life
- divides each cycle into stages
- at each stage, the family changes in predictable ways
EX. marriage, childbirth, child leaving home... In each stage, a family goes through developmental tasks in order to proceed
- failure to accomplish tasks, leads to unhappiness, social disapproval, and difficulties mastering later tasks
- explains the factors that affect differences in behaviour made by people