The purpose of this book is to examine how ideology operates - in the sense of influencing the conduct of inquiry - in the policy sciences, defined as economics, political science, and sociology. In it, Diesing critically explores all the major schools of policy-related social thought from 1930 to 1975. Richard Hartwig, in his new introduction, notes, 'In 1982, Diesing published a remarkable book entitled Science and Ideology in the Policy Sciences. [It] was the best book I had read in a decade, and it related directly to all the policy sciences…. I consider this to be the most brilliant of Diesing's books. Like all of Diesing's works, it remains highly relevant today.'