Constructivism in the International Relations literature mainly focuses on the constitutive interaction between international norms and state actions. Few studies explore when ideas at the domestic level matter in foreign policy change. I propose a constructivist account for policy change that emphasizes not only ideas but also material interests as exogenous factors constituted within domestic structures. My empirical analysis in the case of the Turkish International Cooperation and Development Agency reveals important evidence demonstrating the influence of (i) shared normative values, mostly constituted by the foreign policy elite's intersubjective understanding of Turkey's historical roots and cultural ties in the region and (ii) material interests, favored through the “trading state” and framed by the convergence of principled and causal beliefs on policy change. Ideas matter in foreign policymaking when a set of contingent conditions is satisfied: (i) A small group of recognized foreign policy elite has shared normative beliefs and (ii) an enabling political environment exists, particularly a majority government facilitating foreign policy appointments to key positions so that a window of opportunity is provided for policy entrepreneurship.