An understanding of the consequences of child marriage is important in motivating social change. Using fixed effects estimation (the inclusion of geographic fixed effects at diminishing levels of aggregation and sister fixed effects where possible) on panel data from the Indonesian Family Life Survey (IFLS), we follow the lives of a sample of 40,800 women and men for up to two decades and examine the impact of child marriage on a wide range of variables. We examine the impacts of early marriage on girls, and also boys, and examine the differential effect of girls marrying older versus young males. Child marriage is found to have significant negative impacts on both men and women, including lesser educational attainment, lower earnings and less say in household decision-making. Women are less likely to have a medically-supervised birth and their children are more likely to die, be stunted and perform worse on cognitive tests. Negative impacts are mostly exacerbated when young girls marry similarly young men.