This article stresses considerations in carrying out comparative street gang research, with comparative here meaning cross-national research. The discussion rests heavily on three comparative enterprises: the International Self-Report Delinquency Program, the Eurogang Research Program, and the STAGE proposal from the University of Manchester. All three have involved collaborative efforts of a large number of international scholars over a combined 40 years (and counting). The complexities described include those common to many cross-national studies as well as those most specifically pertinent to street gang studies. Special emphasis in the latter is given over to definitional issues which arise both from the ambiguities inherent in the concept of street gangs and from divergent needs of gang researchers. Also discussed are some emerging issues and selected policy implications. (Published Abstract)