Much of the literature devoted to impact assessment has focused on it as a technique or set of techniques, or on the environmental impact statement as a legal procedural requirement. While there are notable exceptions, the rich theoretical and empirical possibilities for research concerning significant innovations in the way governments operate has not been exhausted. The intention of this new edited collection is to stimulate research on the influence that impact assessment has had on policy making. Bartlett has organized the contributions around the principle that practical effectiveness in the real world of policy-making is determined by the way internal logic and institutionalization redefine policy rationality in a given system. Although impact assessment is defined broadly, the contributors do not focus on the commonalities of the techniques employed. Rather, they explore patterns of institutionalization--the ways that policy is determined through impact assessment. The volume opens with an extensive overview of impact assessment as a policy-making instrument. Other sections are devoted to impact assessment in development planning, future policy directions, and critical perspectives. A comprehensive bibliography completes the work. Building upon several earlier works on impact assessment, this collection combines the insights of pioneering scholars with directions for future research. It is essential reading in the fields of administration, sociology, transportation, business, political science, and urban and policy studies.