When do presidents delegate policy-making authority to their foreign ministries? And is foreign policy unique in this respect? We posit that six international, national, and personal factors determine the opportunity and motivation of presidents to delegate, and then analyse the cases of Argentina, Brazil, and Mexico in 1946–2015. By applying fuzzy-set qualitative comparative analysis, we find that four combinations of factors are sufficient paths to delegation: (1) international stability and elite consensus on foreign policy; (2) international stability, right-wing president, and low diplomatic professionalisation; (3) international stability, right-wing president, and low presidential expertise on foreign policy; or (4) absence of authoritarianism combined with elite consensus on foreign policy and right-wing president. Our study of foreign ministries reinforces some of the main findings of the scholarly literature on other ministries, thus challenging the view of foreign policy-making as different from domestic policy areas.