The article is based on a research of time use in students of a high school in Hanoi. Research findings show a consistency between the theory of time allocation in which individuals allocate more time on a certain activity and less time on the other depending on their own choice. Associations are found in highschool students' personal and family characteristics and their time use. In spite of similar socio-economic conditions, girl students are likely to spend more time on household chores and less time on entertainment than their male counterparts. It is noteworthy that girls allocate more time on self-study at home than boys. Students of the older age group have a larger amount of time for household chores, self-study, and tutoring, but less time for recreation. Family economic status is related to the time students spend on extra classes and entertainment activities, and when their families have a higher standard of living, they have more time to study and play. Thus, is suggested that interventions not only target high school age children, but also need to influence family members' time distribution.