NGOs operate in networks ranging from local to national to international in scale. The shape, nature and strength of these networks will determine the future sustainability of the NGO sector in Indonesia. This brief uses social network analysis to investigate the nature of Indonesian NGO networks as an ecosystem and examine the characteristics of a network based on data from research conducted for the design of the NSSC. The findings indicate that suggest that the stability of NGO networks in Indonesia is still highly dependent on international donor agencies or INGOs. Modelling of scenarios where key hubs were to be taken out of the network structure suggests NGOs would be affected by significant disruption if this were to occur. This analysis suggests that the sustainability of the NGO sector depends on the ability of NGOs to operate in more connected ways. A new imperative to improve ‘network capital’ of NGOs in Indonesia is necessary and important.