Although there is a growing understanding of stalking victimization, it remains difficult to define, and characterizations of the phenomenon vary within the literature. As such, research is needed to understand how variations in the definition of stalking may change who is defined as a victim and thereby limit the generalizability of findings across previous studies. The focus of this study is the inclusion or exclusion of subjective and reasonable measures of fear for 1,430 victims identified by the 2006 Supplemental Victimization Survey. Results suggest that the definition of stalking is important, and prior research has potentially excluded stalking victims due to restrictive operationalizations. Victims who report different types of fear appear to be similar to each other in some respects but differ in others, particularly with regard for gender representation, suggesting some definitions of stalking may be gendered and under-represent male stalking victims. Finally, using complex stratified survey weights, the impact of these varying operationalizations is examined. Using the same data but different definitions resulted in estimates of just over 1 to 5.3 million persons who are stalked in the United States each year.