After the cold war ended in the late 1980s, ASEAN tried to strengthen itself by expanding its members on the hope that an increased in population would translate in to economic growth, and strength. Vietnam joined ASEAN in July 1995, Laos and Myanmar in July 1997, and Cambodia in April 1999. The admission of the four new members noticeably widened the political, economical, and cultural diversity of ASEAN. The ten members states have agreed that political stability and long term economic growth could only be attained if they all cooperate (ASEAN Charter). However, with the expansion of Cambodia, Laos, Myanmar, and Vietnam (CLMV), political and economical disparities have ensued between the old and the new member states. Moreover, the development gap among the member states in the region has also persisted. The challenges of the CLMV countries and the role of development partner will be discussed and examined.