A third of the world's population uses inefficient biomass stoves, contributing to severe health problems, forest degradation, and climate change. Clean burning, fuel-efficient, non-traditional cookstoves (NTCS) are a promising solution; however, numerous projects fail during the diffusion process. We use social network analysis to reveal patterns driving a successful stove intervention in western Honduras. The intervention lacks formal marketing, but has spread across a wide area in just a few years. To understand the process, we map the soCial network of active community members who drove diffusion across a large swath of the country. We find that most ACMs heard about stoves twice before sharing information about it with others and introducing the stove into their own communities. On average, the social distance between ACMs and the project team is 3 degrees of separation. Both men and women are critical to the diffusion process, but men tend to communicate over longer distances, while women principally communicate over shorter distances. Government officials are also crucial to diffusion. Understanding how information moves through social networks and across geographic space allows us to theorize how knowledge about beneficial technologies spreads in the absence of formal marketing and inform policies for NTCS deployment worldwide. (C) 2013 Elsevier Ltd. All rights reserved.