Arthur F. Bentley’s The Process of Government, little noticed at the time of its publication in 1908, greatly influenced the development of political science from the 1930s to the 1950s. Bentley rejected statist abstractions in favour of observable facts and identified groups and their interactions as the basis of political life. Group activity, he argued, determined legislation, administration, and adjudication. In emphasizing behaviour and process, Bentley sounded themes that later became central to political science. In particular, his insistence that “all social movements are brought about by group interaction” is the defining feature of contemporary pluralist and interest-group approaches.