This chapter provides an overview of available data assessing the prevalence of interpersonal violence in sport on an international and a national level. The information is mostly based on estimated figures from retrospective self-report prevalence studies. The majority of these studies focus on sexual harassment and abuse, focus on select victim or perpetrator populations only, and are conducted in Western countries. Due to different methodological approaches used and the lack of consensus on the definitions and manifestations of interpersonal violence, the available prevalence estimates are barely comparable. A scientifically sound tool to measure the prevalence of interpersonal violence in sport is currently lacking. However, in order to convince policymakers of the magnitude of the problem and in order to provide an empirical baseline for prevention initiatives, a standardised, international questionnaire covering all types of interpersonal violence needs to be developed, tested, and implemented in a variety of countries.