This year’s Aid Worker Security Report examines the issue of sexual violence and the differing risks for female and male aid workers in violent operational settings. The Aid Worker Security Database (AWSD) has always tracked incidents of rape and violent sexual assault as a distinct category of attack but Humanitarian Outcomes have not studied the issue in any depth until now. The principal reason for this is the dearth of reliable data to measure the problem and provide an empirical foundation for analysis. While today we see the beginning of better reporting and gender-specific staffing numbers, sexual violence continues to be underreported by an indeterminate but significant degree.