After its transition to democracy and decolonisation in the mid-1970s, Portugal’s main external focus shifted from Africa and the Atlantic to Europe. However, past priorities continued to occupy an important place in its foreign policy. This thesis assesses the impact of European Union (EU) membership on Portuguese foreign policy by focusing on relations with Angola and Mozambique, the two largest former colonies of Portugal in sub-Saharan Africa. The thesis uses the concept of “Europeanisation”, comprising three relevant dimensions for examining possible changes in the foreign policy of an EU member state: national adaptation (a “top-down” process), national projection (“bottom-up”), and identity formation (socialisation process). In order to better control for the influence of other variables (beyond the EU) on Portuguese policy, the concept of Europeanisation is framed within a foreign policy analysis approach. The study focuses on the period between 1978 and 2010, and covers three policy areas: external trade, development aid and political-diplomatic issues. The application of this analytical framework produced significant evidence of Europeanisation, both in its dimension of national adaptation and, chiefly, national projection. The analysis also revealed variations across policy areas and country cases, with the strongest evidence of Europeanisation found for the domain of trade and for the case of Mozambique in general. These findings give support to studies stressing that EU membership “strengthened” Portugal’s postcolonial relations, but also add a more detailed and nuanced understanding of the EU’s impact on the national level.