Two recent decisions by the Swiss and U.S. Supreme Courts allowed a third party to compel arbitration under Article II(3) of the 1958 New York Convention on the basis of an arbitration clause the party had not signed. This contribution critically examines the decisions of these two courts and their willingness to dispense with written consent, or with consent altogether, when it comes to the extension of arbitration agreements to third parties, in view of the purpose and significance of the Convention’s form requirements de lege lata and the role that consent plays in the enforceability of arbitration clauses. The article concludes by considering the extent to which these decisions and other developments in international arbitration reflect a need for reform of the Convention more broadly.