Urban inequality is a major research topic for urban studies and researchers approach the topic in vastly different ways. One takes it as a natural situation simply to be observed, mapped, and measured, a second regards it a blemish on the image of the city and a hindrance to urban competitiveness, while a third might argue it reflects poorly on the quality of urban life and should be tackled with appropriately designed policies. Urban scholars draw their concepts and theories from disciplines such as anthropology, economics, geography, political economy, political science, and sociology. This multidisciplinarity partly explains the different approaches to and analyses of one of its central topics. The approaches to the study of urban inequality have developed in historical periods of interdisciplinary critiques and their responses. Methodologies overlap between periods. The approaches of one period might be heavily criticised and omitted in the second, only to find applications again in the third. This book also adopts an interdisciplinary approach as it draws on political economy and sociology. I draw the main theoretical approaches and analytical concepts from two pertinent critiques of mainstream urban research: critical urban political economy formulated and developed in the works of authors like David Harvey, Neil Smith, Brett Christophers and Anne Haila, and the sociology of territorial stigmatisation introduced by Loïc Wacquant and developed by Tom Slater and several others. In this chapter I introduce some key traditional and contemporary approaches and concepts used in the study of urban inequality within the field of urban studies. This is not an all-inclusive overview but focuses on European and American major research traditions in order to introduce the key influences behind contemporary research on urban inequality in Finland.