Contemporary defenders of philosophical vegetarianism are too often unaware of their historical predecessors. In this paper, I contribute to the rectification of this neglect by focusing on the case of Rousseau. In part one, I identify and articulate an argument against meat eating that is implicitly present in Rousseau’s writings, although it is never explicitly developed. In part two, I consider and respond to two objections that might be made to the claim that this argument should be attributed to Rousseau. In part three, I consider how Rousseau’s argument might fit into a general typology of recent discussions of vegetarianism, and argue that the eclectic nature that is revealed in doing so shows that the argument is worthy of further consideration.