This study focuses on regional networks of interprovincial agreements (IPAs) emerged at China’s Pan Pearl River Delta (PPRD). Coparticipation of eleven PPRD members in 192 IPAs is investigated. It examines the extent to which coparticipation in the seven policy areas by the PPRD members are correlated. It measures density, the degree to which PPRD members coparticipate in IPAs. Although regional economic development was the initial focus, more IPA coparticipation has been devoted to addressing the noneconomic policy concerns. The results of the study are relevant for understanding the complex patterns of regional collaboration in which subnational governments participate.