INGOs have proliferated globally despite a sharp decline in new U.S.-based foundations between 1992 and 2012. This paradox stems from environmental density, which discourages founding while encouraging competition among established organizations.

Key finding: Density correlates negatively with INGO founding rates across sectors.

Why it matters: This research reveals an overlooked causal mechanism—density—in shaping the international NGO landscape, addressing ongoing debates about cooperation versus rivalry.

Data & methods: Analysis of a new comprehensive U.S. dataset (1992–2012) and case studies in environmental conservation and democracy assistance sectors.