Non-completion of senior secondary schooling continues to be a matter of concern for policy makers and practitioners in Australia today. Despite the efforts of governments to improve participation and retention rates, 30% of students drop out of school before completing Year 12. Further, some students remain at school, just biding their time until graduation. Within this context, we investigate whether the wellbeing of the students is a key factor in supporting senior students in deciding to continue at school. The article reports on the first phase of a two-year study of factors impacting on quality retention and participation of 250 Year 11 students from two school communities. This initial phase focuses on the senior students' perspective of their wellbeing in Year 11, and includes our development of a suite of scales to measure the impact of students' social connectedness and academic engagement on academic achievement and retention. Data from the survey of students are enriched through student focus groups. The article identifies critical dimensions of what students regard as a healthy senior school culture; that is, a culture conducive to a positive and productive experience in terms of their retention, participation and achievement. Implications for school and system policy and governance are proposed. (Contains 6 tables, 1 figure and 1 endnote.)