“Horizontal” and “vertical” diffusion: The cumulative influence of Impact and Benefit Agreements (IBAs) on mining policy-production in New Caledonia

► Localized mining firm-community negotiated agreements (IBAs) contribute to mining policy making. ► IBAs' negotiation and implementation defines a complex arena of social actors and institutions. ► IBAs' “diffusion” includes “horizontal” (to communities and firms) and “vertical” (on policy). ► Diffusion may be “positive”, effecting further change, or “negative”, making change less likely.