This article begins with a review of the historical development of Canada's Immigration and Refugee Board (IRB) guidelines on gender-related persecution which were adopted in 1993. The author discusses the rationale behind the adoption of the guidelines, namely the recognition that many women are persecuted solely on the basis of their sex. The author explains how the IRB implemented the guidelines and how the Canadian courts have interpreted and endorsed the guidelines, such that gender is now considered as a basis of "particular social group" for the purposes of the 1951 Refugee Convention.