It is often difficult to establish a common ground for discourse between researchers, practitioners and policy makers interested in cities. This is not only because the terminology used is occasionally charged with context-specific meanings, but also because basic concepts - and especially that of the ’urban’ - are sometimes only loosely defined. Bringing together leading academics and professionals from a range of fields as diverse as anthropology, architecture, ecology and economics, including Saskia Sassen, Neil Brenner, Eric Strause, Setha Low, Susan Saegert, Allan Cochrane, Peter B. Meyer and Sarah Ichioka, this edited volume provides a comprehensive overview of and insights into what the term ‘urban’ means. It identifies and critically examines the most important theoretical perspectives, and practical dimensions for the study of cities. In particular, it focuses on how the overlaps and creative merges between these different academic disciplines and professional fields can give rise to a multitude of diverse interdisciplinary approaches and tools that can be used to explain or guide ‘urban’ processes. The volume not only crosses academic boundaries but will also bridge the divide between urban theory and practice. Structured in three parts, the first and second part, ‘Theories’ and ‘Practices’, are concerned with the ways in which the academic disciplines and professional fields, respectively, associated with urban research (e.g. Ecology, Economics, Geography, Sociology) or practice (e.g. Architecture, Planning, Social Work) approach the city. The third part, ‘Emerging Approaches and Tools’, outlines how elements from the different academic disciplines and professional fields combine to form transdisciplinary tools and perspectives.