In the aftermath of the "explosion" of "hard" data sets in the 1960s for the study of international relations, there has been a movement back toward the use of various experts to quantify the more elusive aspects of the international situation. These aspects range from the beliefs and perceptions of decision makers to the array of stresses that confront nation-states both internally and externally. This volume reflects the most recent and innovative work in the use of data generated by academic, policy, and other experts. The authors discuss expert-generated data as a means of data making, data refinement, and policy analysis. They present all of the major expert-based approaches and offer a variety of methodological and substantive applications.