When attribution of responsibility is not clear, political alignments are irrelevant for shaping the successful implementation of national social policies. This is the case of the selected health policies in Brazil (Estratégia Saúde da Família) and Argentina (Plan Nacer). For each country, the Chapter first analyzes the sources of blurred attribution of responsibility and, as a consequence, the irrelevance of political alignments. Second, it focuses on the role of policy legacies within each national health policy. Entrenched interests from a previous primary healthcare strategy and from high-complexity health provision are crucial for understanding the challenges in the implementation of Estratégia Saúde da Família in Brazil. The states and municipalities that had a more developed health structure present the greatest resistance to this policy. Finally, territorial infrastructure is central for understanding the successful implementation of national health policies. In Brazil, municipalities –in coordination with civil society – are in charge of implementing primary healthcare, and states are more or less present in coordinating such provision. In Argentina, provinces provide healthcare but some municipalities in some provinces have also taken on health responsibilities.