Transnational public-private governance initiatives (TGIs) in which governments and/or formal intergovernmental organizations, business, and civil society organizations cooperate to govern global problems have become an important element of world politics. In many issue areas, TGIs co-exist with other TGIs. This co-existence creates room for institutional overlap that is observable in the form of networks among TGIs. While in some issue areas the overlap among TGIs has been rapidly growing, in others it has been characterized by a mixed pattern of growth and decline, and in still others it has stagnated. What explains this variation? I use network analysis to examine the evolution of the overlap among TGIs through shared state participants across issue areas and over time. I find that TGI overlap is facilitated by a shared issue area focus and the size of TGIs as well as clustering and popularity within the TGI network.