School-related violence is a major challenge in many low- and middle-income countries. This is well established by surveys that - if anything - likely underestimate the prevalence of violence in schools. Yet prevalence rates on sexual, physical, and psychological violence are just the first piece of data that policymakers and partners need to combat school-related violence: they also need data on which groups experience violence, which groups commit violence, where and when violence is taking place, and whether it is getting better or worse over time. In this study, we review the availability of data on school-related violence from international surveys administered across low- and middle-income countries as well as national surveys in a sample of countries over the last decade. We find that most countries lack data to answer simple questions that policymakers might ask as precursors to taking action against school-related violence, to understand the consequences of violence, or to monitor progress on reducing violence. For example, only one in six countries has data to measure how many children have recently experienced sexual violence from school staff, none of the countries has the data to track dropouts in the year subsequent to an incident of violence, and none of the surveys could identify how much violence occurs on the way to and from school. The gaps in data are biggest for younger children. We provide a dataset of international surveys with school-related violence questions and recommendations to improve measurement of school-related violence to increase actionability by decision makers in education systems.