Abstract This chapter summarizes the problems with measuring the prevalence and severity hate crimes in the United States that are delineated in greater detail in later chapters. The chapter explains the various types of contemporary hate crime legislation with a focus on their similarities and differences and ramifications for accurately measuring the prevalence of hate crimes. The chapter examines federal and state variations in statutory provisions with particular emphasis on differences in statutorily protected bias groups and evidentiary criteria. This chapter focuses in some detail on evidentiary criteria including discriminatory selection, animus, “because of” and “by reason of” evidentiary standards. The chapter also summarizes landmark supreme court decisions that have set the legal parameters for the promulgation of federal and state hate crime statutes within the constitutional constraints of the First and Fourteenth Amendments. This chapter concludes with a discussion of the importance of accurate measurement as it relates to enacting evidence-based policies and practices that serve the most vulnerable and likely victims of hate crimes.