In this paper, we take the view that school classrooms are spaces that are constituted by complex power struggles (for voice, authenticity, and recognition), involving multiple layers of resistance and contestation between the "institution," teachers and students, which can have profound implications for students' science identity and participation. In particular, we ask what are the celebrated identity performances within science classes, how are these re/produced and/or contested, and by whom? Analyzing data from 9 months of observations of science classes with nine teachers and c. 200 students aged 11-15 from six London schools and 13 discussion groups with 59 students, we identify three dominant celebrated identity performances ("tick box" learning, behavioral compliance, and muscular intellect) and discuss the complex ways in which these are promulgated both institutionally and interpersonally by teachers and students, drawing out the implications for students' performances of science. The paper concludes with reflections on the equity implications for science education policy and practice.