This paper is an extension of the author's earlier work on developing management information services and creating a culture of assessment in libraries. The author will focus observations on the use of data in decision-making in libraries, specifically on the role of leadership in making evidence-based decision a reality, and will review new opportunities for data analysis, assessment delivery, and decision-making in libraries. Developments in the information technology (IT) area, especially the increased dominance of very large networked infrastructures and associated services, large-scale digitization projects, collaborative frameworks, and economic and market trends, may have a positive impact on library options for data use and analysis by library management. The discussion is informed by a wide range of new products and services, which are becoming available in the marketplace and are designed to assist decision makers, and by interviews conducted by the author with over 20 library directors, mostly from the Association of Research Libraries. (Contains 44 notes.)