The literature on economic sanctions consists of a series of studies assessing whether sanctions ''worked'' or not. Very little has been written on the factors that make economic sanctions more effective at achieving their intended purposes. This article examines the threatened 1979 Arab world boycott of Canada after Prime Minister Joe Clark announced the government's intention to relocate its embassy in Israel from Tel Aviv to Jerusalem. After determining that sanctions played a contributing role in motivating a Canadian policy reversal, it generates hypotheses from this misunderstood case about the political and economic factors that can contribute to the success of economic sanctions.