This article examines Oxfam GB's learning from its attempts to improve monitoring and evaluation (M&E) processes within a global advocacy campaign. It outlines the Climate Change campaign team's practical experience of piloting different approaches to M&E, and the lessons emerging from the process. The experience suggests that while some 'traditional' elements of M&E are helpful in advocacy work, a greater focus on light, real-time monitoring systems is necessary. The findings highlight the organisational as well as methodological challenges of integrating M&E into advocacy campaigns: without a culture that rewards reflection and learning, improvements in staff capacities or data-collection systems will not be sustained. Indeed, the process of improving M&E practice mirrors that of an advocacy campaign itself, requiring analysis of power relations, opportunities, and constraints; monitoring of progress; and adapting plans on the basis of on-going learning. Finally, the article suggests possible ways forward, based on experience.