This brief, prepared with funding from GPE and other partners, summarizes findings from research undertaken by Save the Children and the World Bank on the lack of legal protection against child marriage for girls and marriages that take place below the national minimum age of marriage. The analysis suggests that many countries still do not effectively legally protect girls against child marriage, but also that legal reforms are not sufficient to end the practice as many girls marry illegally in countries where legal protections are in place. While protecting girls in the law against child marriage is an important first step, additional interventions are needed to prevent child marriage.