In the age of globalization, new regionalism has become a new trend of regional development. This study examines the making of new regionalism in South China, using the case of Hong Kong-Shenzhen region. By tracing the process of Hong Kong and Shenzhen integration during the past three decades, the research finds three stages in Hong Kong-Shenzhen regionalization after the late 1970s, namely, the emergence of informal regional society from below, the transitional regional society and formal regional society, with reference to Hettne's concept of regionness. Hong Kong's internal economic, political and societal difficulties and external changing conditions are conducive to Hong Kong government's re-regulation toward a more positive stance on cross-boundary regionalization. Although intense economic and social interactions exist between Hong Kong and Shenzhen, a cross-boundary regional community has not emerged yet. The slow development of cross-boundary regional community is different from European case. The active participation of the governments aims to facilitate cross-boundary economic and infrastructure development and planning. This can take place well before reaching higher level of regionness: the formation of a regional community or the regional institutionalized polity.