The major issue in the Shanghai Cooperation Organization (SCO) has been the problem of enlargement of its full membership. Traditionally this issue is reviewed as a problem of practical policy. However as debates on the SCO membership enlargement progress, they go into more and more depth. This enlargement debate highlights political culture of SCO and also the issue, known in the experience of other international organizations, namely emerging different levels in an organization as membership grows. More importantly debates on enlargement stimulate thinking over the broader question on the future of the SCO - the global perspective (as Russia mostly prefers) or regional perspective (as China mostly prefers). Thus SCO encounters one of the most pressing dilemmas, that's collision of regionalization and globalization trends progressing in the modern world. Debates on these trends evolve in political, economic and social sciences and remain far from resolution. But the SCO is already under the pressure to make either a practical choice in favor of one of these trends or to find a reliable model to combine them within the SCO agenda. This article reviews the SCO enlargement problem not as an issue of practical policy, but as the issue of searching a balance between trends of globalization and regionalization, which if reached could help to reconcile Russian and Chinese interests in Eurasia.