This article studies the effect of birth order and low household economic resources on school attendance and labor market participation among the population of minors in Mexico. Drawing on data from the Child Labor Center, this work estimates a series of multivariate probit models with different specifications, aiming to minimize problems related to the endogeneity of the sample. The analysis reveals that first-born children are less likely to attend school and more likely to participate in the labor market than their siblings. This relationship is stronger in families where child labor is a response to a lack of economic resources, which suggests that it is the result of the greater income-earning capacity of first-born children.