Otto Weininger was one of the most controversial and widely read authors of fin-de-siècle Vienna. He was both condemned for his misogyny, self-hatred, anti-semitism and homophobia, as well as praised for his uncompromising and outspoken approach to gender and morality. The purpose of this new collection of essays is to explore the various ways in which Wittgenstein absorbed and responded to Weininger's ideas. Written by an international team of experts on Wittgenstein and Weininger, the volume is especially timely in the light of recent translations of Weininger's work.