There were at least four situations in which European and American stances over how international politics should be conducted clashed and in which Romania was pressured to take one side or another: International Child Adoptions, Kyoto Protocol, International Criminal Court and War in Iraq. Why did Romania decide to align sometimes with the US and other times with European countries? This paper uses the explanatory power of three leading theories of international relations to explain this puzzle. Firstly, it shows that systemic forces of power relations are suitable for explaining state behaviour, but only in security-related matters (neo-realism). Secondly, it shows that public opinion is not translated into government policy either because public interest is lacking or information about public’s preferences is not available (liberalism). Thirdly, it shows how inter-subjectively shared meanings, identity recognition and socialisation of new norms offer the most compelling explanations about Romania’s behaviour in the four situations of transatlantic divergences (constructivism).