Empirical evidence shows that lack of resources during infancy and the process of accumulating disadvantages throughout childhood have important consequences for cognitive and socio-emotional development. This paper examines socioeconomic gradients across language and socio-emotional measures. Using longitudinal data from 7-year, three-wave panel data, we study the patterns of socioeconomic status and child development in Chile and estimate how much of the wealth gap can be explained by different mediators like maternal educational and skills, child attendance of preschool and school, possession of books, or domestic violence indicators. We show that there are strong associations between household wealth and child development, and that, as the child grows, the gap between the most extreme quintiles of the distribution, both in cognitive and socio-emotional skills, persists but decreases in magnitude. Taking advantage of the longitudinal nature of the data, we calculate a permanent skill for each child and each skill dimension in this 7-year period. The analysis for the permanent component shows that wealth gaps are important to determine language, but not socio-emotional skills, and that the gap is larger for girls than for boys in the early childhood period. While mediators account for some of the associations, there is still a large socioeconomic gap that persists in receptive language among children. The most important factors that mediate the wealth gaps are inherited from maternal characteristics. By understanding the dynamism of social and cognitive vulnerability experienced during childhood and employing longitudinal data and methods, this study contributes to and extends the existing literature on socioeconomic gaps and child development in the Latin American context.