Data collection methods and poverty measures have not caught up with the reality of an increasingly urbanised world; as a result, it is increasingly likely that urban poverty is underestimated. This has important implications for targeting interventions and allocating resources in the 2030 Agenda for Sustainable Development over the next 15 years. This report explores the current problems with the definition of 'slum' settlements and data collection in urban contexts and provides recommendations on how to address and improve the identified issues.