Abstract
The quantitative evaluation of science, now in its second generation, has become a policy-oriented specialty. Second-generation bibliometrics, as represented by several new approaches, has transformed the analysis of publication and citation data into a sophisticated tool for comprehending the complexity of the scientific enterprise and for addressing practical issues on the national and world science policy agenda. By developing quantitative measures of research performance, second-generation bibliometrics has improved the scope and relevance of science output indicators and, to a lesser degree, indicators of the institutional structures that mediate science and society. These improved output measures are essential components of social impact of science (SIS) indicators, which represent in quantitative terms the conjunction of science indicators derived from second-generation bibliometrics and available social indicators.