This dissertation investigates how the strategic tool of internationalization can be used by International Non-Governmental Organizations (INGOs) in the advancement of their missions. The purpose of this study is to analyse if this strategy has helped these organizations achieve their long-term missions of eradicating poverty. The literature discusses the changing roles of NGOs in a globalized world alongside the increasing pressures for the Third Sector in terms of competition, accountability and transparency. A case study methodology is adopted referencing Yin (2009) and the advantages that this research method can have for management studies. A case study comparison is utilised when comparing ActionAid International who began its internationalization process at the end of 2003 when moving their headquarters (HQ) to Johannesburg, South Africa. In contrast, Oxfam International plans to relocate HQ to Nairobi, Kenya in 2017. The results of the study illustrate that internationalization is a complex phenomenon and both case studies had different reasons for adopting the strategic tool. This research paper hopes to provide value research for NGO managers who may decide to internationalize in the future. Limitations of the study are due to the results being from the perspective of both the organizations under investigation. Further research is recommended to analyse the effectiveness of Oxfam International after its internationalization has been completed. Alongside the task of developing a universal measure for measuring the effectiveness of INGOs.