The article reports on research undertaken in 2009 to examine factors affecting the retention of students in senior secondary physics. The study involved Year 11 students from nine schools in western and northern Sydney. The study found that students’ main consideration for staying with or leaving physics was their perception of how it would affect their ATAR scores, and thus their opportunities for tertiary entrance. Pessimism about their prospects was the main driver for dropping out. For this reason, it is of key importance that teachers and schools support students’ self-concept as learners of physics. One of the main ways to do so is to challenge the individualistic, competitive mindset generated by end-of-year summative assessment and rivalry for tertiary placement, by encouraging cooperation and mutual support amongst students.