An article for the first issue of [Policy Sciences], of which Dror is an editor. A clear definition of policy sciences is urgently needed to protect the term from misapplication. Policy sciences is a supradiscipline focused upon public policymaking methods, using behavioral and physical sciences and integrating many analytical approaches. It differs from system analysis by (1) tackling much broader, more complex, and more ill-defined problems that are nonquantitative; (2) considering political feasibility, consensus maintenance, and the social power implications of alternative policies; (3) recognizing the importance of the extra-rational and irrational; (4) seeking to encourage creativity and "organized dreaming"; (5) seeking to distill the tacit knowledge of experienced decisionmakers; (6) recognizing others' value systems (e.g., self-sacrifice or revenge rather than economy and efficiency); and (7) deliberately shaping its own future and educating to overcome the trained incapacities of workers in the normal social sciences and decision sciences. 35 pp.