Comparative studies of criminal justice across nations and cultures are no less challenging. They confront criminologists with numerous methodological problems. These range from the pitfalls of data collection to epistemological questions of cultural relativism, the general possibility of taking comparative studies beyond the in-depth analysis of a single case, the limitations of understanding a culture that is not our own, and the risk of overgeneralization. Susanne Karstedt's chapter provides insights into the methods used by comparative criminologists when navigating these problems. The chapter starts with a brief overview of the expanding field of comparative criminology, and its links with processes of globalization. Throughout Karstedt reveals the wealth of opportunities open to criminologists willing to engage in cross-cultural research, in particular the ever-increasing range and accessibility of data sources for comparative studies of crime and criminal justice. The chapter moves on to identify the two major methodological challenges for cross-cultural research: the problem of autonomy of the sphere of culture; the problem of coherence and homogeneity of culture in contrast to its internal differences and variation; and finally the question of understanding, interpreting and analyzing a culture that is not the researcher's own. General comparative strategies that address these problems are presented, and questions of practical research design are discussed: selecting units, cases and samples; and identifying, reconstructing and measuring culture. The chapter concludes with an outline of new methodological challenges that arise from migration and the study of minority cultures in multicultural societies, and from more rapid cultural change.