The discussion begins by profiling and criticizing an admittedly extreme view, one in which the development of policy is based on the development of the knowledge on which the policy could be based. To widen conceptions of possible connections between knowledge and policy, the author outlines some alternative images of how society develops and uses knowledge in confronting other social problems, specifically, the problem of agricultural development, the treatment of cancer, and the establishment of civil rights. These different systems will be presented as different choices about how to structure the relationship between knowledge and action on the following dimensions: whether action waits on or occurs in advance of the accumulation of validated findings, whether "experts" or "lay" actors are authorized to act, and the overall organization of the effort to capture the learning that comes from field experience. The author then uses various sketches to do analytic work that helps form preliminary judgments about how the relationships between research and policy should be structured in two initiatives that have been emphasized in the United States: efforts to expand community policing and to prevent youth violence. The paper concludes with observations about how social scientists might better deploy themselves to be of greater use to society in helping it confront problems. 41 references