As feminist theory has taught us, gender difference and sexual difference are a continual work-in-progress. Our culture works hard to forge and maintain femininities and masculinities, and to create women and men. On one hand, the incessant ubiquity of this labour makes it often invisible, and accordingly natural: it seems to be just the way things are. On the other hand, the degree of energy and force expended in this project – the stridency by which our masculinities and femininities are continually announced, expressed, maintained, celebrated – suggests something desperate, strained and fragile about this whole project. Continually revealing the labour that goes into being men or women – showing just how strenuous those efforts are, and asking who suffers as a result – is the critical task of feminist, gender and queer critique. That critical work is never done, because the work of gender and sexual differentiation is never done. What can human-animal studies contribute to feminist and queer critique? It allows us to understand the intersections between the work of gender and sexual differentiation and the work of human-animal differentiation. Everything we do to animals, and with animals, is intimately mingled with our ideas about, and our ways of living, gender and sexual difference. And vice versa: how we think about and how we live gender and sex, including sexuality, are shaped by our perceptions of animality.