This chapter examines the relationship that Asia-Pacific regional and sub-regional organizations have with international law, looking at seven international organizations that span the region. It is commonly believed that the member states of Asia-Pacific regional organizations prefer less formalized institutions and fewer binding commitments. Conventional reasons for this include their history of colonialism, less legalistic and formalized cultures, and a preference for stricter conceptions of sovereignty. As such, their organizations are often perceived as less effective. However, the effectiveness of Asia-Pacific regional institutions should not be judged by one uniform standard. Instead they should be judged on their own definition of effectiveness. There should be a broader understanding that Asia-Pacific states consciously use and participate in their regional organizations differently than in other regions, and they may prefer less institutionalized models as these serve their purposes better and can still be successful.