The notion of systems has helped revolutionize translation studies since the 1970s. As a key part of many descriptive approaches, it has broken with the prescriptive focus on what translation should be, encouraging researchers to ask what translation does in specific cultural settings. From his privileged position as a direct participant in these developments, Theo Hermans explains how contemporary descriptive approaches came about, what the basic ideas were, and how those ideas have evolved over time. His discussion addresses the fundamental problems of translation norms, equivalence, polysystems and social systems, covering not only the work of Levý, Holmes, Even-Zohar, Toury, Lefevere, Lambert, Van Leuven-Zwart, Dhulst and others, but also giving special attention to recent contributions derived from Pierre Bourdieu and Niklas Luhmann. An added focus on practical questions of how to investigate translation (problems of definition, description, assessment of readerships, etc.)