There has been unprecedented progress in important aspects of the lives of girls and women over recent decades. Yet even where gender gaps are narrowed, systematic differences in outcomes often persist. These deprivations and constraints sometimes reflect persistent violations of the most basic human rights. This is a major new report that shines a spotlight on the value of voice and agency, the patterns of constraints that limit their realization, and the associated costs. The vast data and thousands of surveys distilled here cast important light on the nature of constraints women and girls continue to face globally.