Providing a curriculum that promotes personal growth and wellbeing is an overarching learning outcome of the Western Australian Curriculum Framework (Curriculum Framework, 1998). However, little is known about what constitutes and causes wellbeing of students in our primary schools. In the study reported in this paper the happiness of 312 primary-aged students was measured using various instruments and viewpoints, along with demographic information provided by their parents. The findings, which were compared with Holder and Coleman (2008) and research into adult happiness, indicate that a sense of friendship, belonging and optimism are strong indicators of children's happiness. (Contains 6 tables.)