In the Sudan Accountability and Divestment Act (‘SADA’) of 2007, Congress authorized state governments to divest from businesses investing in Sudan. Congress took this unprecedented step in the face of objections from the Bush Administration and the business community that state divestment intrudes unconstitutionally into the exclusive foreign-relations prerogatives of the federal government. SADA would be remarkable enough if it allowed state divestment while adhering to a dualist conception of federalism. This paper explores the possibility that SADA and its progeny – the Comprehensive Iran Sanctions, Accountability, and Divestment Act (‘CISADA’) of 2010 – may signal the emergence of a dialogic view of federalism, under which the federal government recognizes that states may legitimately speak on international concerns within bounds that preserve ultimate federal control over foreign relations.