In Southeast Asia, a unique situation has existed for decades where political, economic, military and cultural relations flourish between Southeast Asian countries and Taiwan in the absence of official diplomatic relations. The Taiwanese economy is very important to Southeast Asia, yet Taiwans unresolved political unification with the Peoples Republic of China is a threat to the security of Southeast Asia. In many ways, Taiwan is the elephant in the room despite their importance, studies on Southeast Asia have largely neglected the existence and the durability of the ties between Southeast Asian countries and Taiwan. To find out what motivates Southeast Asia to maintain relations with Taiwan and vice versa, this thesis investigates the bilateral developments between Taiwan and Southeast Asia by conducting a comparative assessment of Vietnam and Singapore. The focus of the thesis is on the period between 2000 and 2016, as there is scant research on Southeast Asia and Taiwan during the last sixteen years. The thesis examines key dimensions of the bilateral relationships and a number of hypotheses that are found in existing literature. The research found that the hypotheses only partially explain the reasons for changes in relations. For Vietnam and Singapore, economic interests and security concerns are the main reasons for engaging Taiwan. Based on the evidence gathered, this thesis also analyzes Vietnam and Singapores responses to the new Taiwanese President, Tsai Ing-wen.