At a symposium of the American Society for Tropical Medicine and Hygiene (ASTMH) Annual Meeting, I explored how peer learning could help us tackle five critical challenges that limit effectiveness in global health. For epidemiologists working on implementation science, peer learning provides a new path for solving one of global health’s most persistent challenges: how to reliably spread evidence-based practices at the speed and scale modern health challenges demand. The evidence suggests we should view peer learning not just as a training approach, but as a mechanism for viral spread of effective practices through health systems. How do we get to attribution? Of course, an epidemiologist will want to know if and how improved health outcomes can be attributed to peer learning interventions. The Geneva Learning Foundation (TGLF) addresses this fundamental challenge in implementation science – proving attribution – through a three-stage process that combines quantitative indicators with qualitative validation. …