Using all the household survey data available in Latin America during the period 1992 to 2013, this paper estimates that in 2015, 20 million youth ages 15 to 24 years in the region were out of school and not working (making them ninis, for "ni estudian ni trabajan"). The share of out-of-school, out-of-work youth in Latin America, at about 19 percent, is roughly equal to the global average of 22 percent. Although women make up over two-thirds of the ninis in the region, the number of male ninis grew by 46 percent between 1992 and 2010. As a result, the absolute number of ninis rose over the two-decade period, even as women's education and employment rates were improving. Global comparisons show that Latin America is the region of the world with the largest concentration of ninis among households in the bottom 40 percent of the income distribution. Coupled with the long-lasting harm it causes to the youth's future labor-market outcomes, the high incidence of ninis among the poorest households tends to lock in income disparities from one generation to the next, obstructing social mobility and poverty reduction in the region.