Urbanisation in low-income countries is one of today's global challenges: managing rapid urbanisation with the right policies is key to tackling urban poverty, inequality and achieving the Sustainable Development Goals. Rapid urbanisation means that cities are densifying and expanding into their peri-urban hinterlands at an unprecedented pace, while governments struggle to plan and provide urban services at scale. As a result, residents settle in unplanned areas, where land, housing and infrastructure are accessed and regulated through hybrid regulatory systems, transcending social norms, customary law and state law. However, the ways in which de facto rights work for residents remains a mystery to researchers and policy makers, resulting in inadequate policy approaches. What are the strengths and weaknesses, diversity and adaptability of these social norms in different countries, cities and settlements? What are the policy needs and priorities in diverse contexts? The MetRe project develops and applies new methodologies to answer these questions and develop tailor-made policy responses by measuring the social regulation of land and other urban resources on the ground. Interdisciplinary collaborations and co-design initiatives with local stakeholders are the foundations of MetRe: we welcome expressions of interest to collaborate in research, training or dissemination.