Measures of cost efficiency, including cost/benefit and cost-effectiveness estimates, are important for evaluating prevention programs. Since the 1990s, cost/benefit analyses of a wide assortment of negative social conditions have become very popular in countries worldwide. In this entry, we rely on examples of studies related to family issues, breastfeeding, work/family policies, and violence against women, in order to highlight a trend in the use of cost/benefit analysis. Over the past decade, cost/benefit studies have often been used as claims-making activities in the construction of social problems and to build a rationale for preventive action.