Final answer:
The period of family life when the grown children depart from home is known as the Launching Family stage, which is part of the family life cycle.
Step-by-step explanation:
The stage of family development where grown children depart from home is known as the Launching Family stage. This stage is part of the family life cycle, a concept which has been used historically to describe the predictable stages and patterns that families go through over time.
The family life cycle includes various stages such as Marriage Family, Procreation Family, Preschooler Family, School-age Family, Teenage Family, Launching Family, and Empty Nest Family. Each stage presents unique challenges and achievements, and the success of a family can often be measured by how well they adapt and transition between these stages.