Economia / Master in Economics / The relevance of foreign direct investment (FDI) (UNCTAD, 2007) is recognised by a vast body of literature. However, until recently most studies and policy-making initiatives were focused on the mere magnitude of FDI inflows (i.e. the quantity), neglecting the quality of these investments. Recent literature on subsidiaries roles and evolution is shedding light on the asymmetric quality of multinationals (MNEs) operations, hence helping to understand their differentiated impact on host economies. This dissertation contributes to this literature by investigating empirically the quality of foreign subsidiaries activities located in Ireland and Portugal. Using data from a purposely designed questionnaire survey, the following questions will be analysed. First, which characteristics of multinational subsidiaries are conducive to innovation? This study will consider the impact of age, education and R&D intensities, among other characteristics, on innovation. This question will be analysed using a probit model. Second, do foreign subsidiaries based in Ireland and Portugal differ in a systematic way with regard to these characteristics and with regard to the motivations that led to their establishment? This question will be studied using nonparametric methods. The empirical results (first application) corroborate the hypotheses that age, education and R&D intensities of the subsidiary impact positively on innovation. The results are consistent with previous studies that emphasise the time dependent aspect of multinational subsidiaries evolution (Young, Hood and Peters, 1994; Birkinshaw and Hood, 1997, 1998) and those that highlight the importance of human capital (Bartel and Lichtenberg, 1987; Narula and Marin, 2003) and R&D activities (Cohen and Levinthal, 1989, 1990) for technology absorption and creation. It was also found (the second empirical application) that the asset-seeking motivation played a more important role in attracting investors to Ireland than to Portugal and that subsidiaries based in Ireland tend to display greater education and R&D intensities than those based in Portugal.