Wealth-ranking is a participatory tool enabling people to group others in their community into wealth bands, and thus identify the very poor. The method has been developed to include the broader aspects of well-being – such as social standing and health – that people value as much as material wealth. It tells the story of the development of these assessment methods since the rise of wealth ranking in the 1980s and looks at the results of well-being ranking exercises and how they help identify important differences within communities and monitor changes in well-being over time. Exploring strengths and weaknesses of methods it suggests that understanding differences within communities is essential for good development aid work. The book goes on to describe the successful use of ranking tools over large populations and the value of using multi-dimensional models of well-being, and briefly explores the ideas used to make assessments of well-being at national levels.