The participation rates of girls in post-compulsory information technology courses of Australian universities and high schools have remained low (less than 30%), despite three decades of research and analysis. In seeking to better understand this phenomenon, this paper draws upon data collected during an Australian Research Council Linkage project to investigate first, the reasons that teachers and students in contemporary Australian high schools put forward to account for girls' underrepresentation; second, the assumptions about gender that underpin these explanations; and third, the extent to which teachers appear able to respond to the full range of factors shaping girls' decision making. The paper argues that attempts to improve girls' participation rates might continue to falter unless teacher education programs explicitly prepare teachers to conceptualise educational reforms based on understandings of post-structural perspectives on gender; perspectives that challenge the more common explanations for girls' behaviour associated with both essentialist and socialisation mindsets.