U.S. government claims of support for the global nonproliferation norm sometimes appear contradicted by dramatic changes in its policies regarding support for peaceful nuclear energy programs around the world. This study offers a new accounting of foreign policy decision making relative to global nonproliferation normative architectures as a product of norm-based differences between presidents and congressional leaders over technology sharing. It advances an agentic constructivist model of the export policy process and conducts a plausibility probe of the model through three case studies of export control reform debates. It also examines alternative theory models focused on strategic imperatives, foreign policy change, and neoliberal economics. Case evidence suggests that different alignments in norm stewardship, and the interactions of key agents regarding perceived norm commitments, help account for export policy struggles. These often translate into unique and complex policy outcomes, suggesting the value of contingent models of policy change and international cooperation.