On September 22, 2015, the Democratic Progressive Party (DPP) announced a New Southbound Policy during the presidential election campaign. The Policy is defined as a multi-faceted initiative to enhance Taiwan's engagement in Southeast Asia. As President Tsai Ing-wen articulated the New Southbound Policy in her inaugural address, it has become a crucial element for Taiwan's economic and trade strategy. This paper contends that the New Southbound Policy is not only an external economic policy, but a tactful and proactive way to simultaneously re-orient Taiwan's national development with its international participation in the regional community. Moreover, it argues that, for success, the New Southbound Policy needs to prioritize mutual interests between Taiwan and Southeast Asia that are contextualized in the process of the ASEAN Community. This paper begins with the introduction of ASEAN integration and regional dynamics of Southeast Asia. Then, it discusses the background of New Southbound Policy proposed by the DPP and emphasizes the framework and issue areas of prioritizing mutual interests between Taiwan and Southeast Asia.