I examine the question of what motivates family members to live apart or together, using the Japanese Panel Study of Consumers. I attempt to explain family living arrangement by two forces, dispersing and assembling. Considering family members live together to reduce their cost of living, financial wealth functions as dispersing force, while large dwelling size works the other way. Another assembling factor is care-giving. Parents see their adult daughter as a potential caregiver while daughters expect their elderly parents to give care to their children. I find that financial wealth and large dwelling function as the most important factors for family living arrangement.