Thesis: In this thesis, I combine objective and subjective approaches to poverty to examine poverty thresholds, their determinants, and the overlap between monetary and multidimensional poverty. My relative approach aims to identify populations that stand out due to their perception of their situation, practices, or treatment, aligning with the definition of poverty as social exclusion rather than merely low income. I use longitudinal data and variables to quantify subjective experiences such as life satisfaction, financial situation, housing, feelings of social exclusion, and self-reported health status, comparing these with the objective definition of poverty based on living standards relative to median income. My work focuses mainly on France, with a comparative study in Chapter 1 between France and other countries (Germany, the UK, Australia) with similar monetary poverty rates. In Chapters 1 and 3, I explore new ways to define poverty using self-reported well-being (Chapter 1) and individual preferences (Chapter 3), addressing economic vulnerability and the accumulation of deprivations. Chapter 2 quantitatively addresses the relative importance of the determinants of social exclusion in France, testing whether they are objective or linked to the perception of social benefits. The three essays in the thesis aim both to deepen the understanding of poverty through individual experiences and to propose indicators for public policy. The thesis advocates for a combined approach to monetary and non-monetary dimensions of poverty, suggesting a distinction between extreme poverty and economic vulnerability, and a multidimensional indicator for deprivation accumulation. It also calls for a broader debate on the social justice concepts underlying poverty indicators.