The Causal Effect of Speaking Spanish as an Additional Language on Education, Labor, and Wellbeing Outcomes, Among the Indigenous Ethno-Linguistic Minorities of Mexico

We estimate the effect of speaking Spanish as an additional language (SAL)—as opposed to speaking it as a native—on education, labor, and wellbeing outcomes among Mexico's indigenous ethno-linguistic minorities. Controls are appropriately comparable indigenous individuals who speak only Spanish. To address treatment endogeneity, we use 2SLS, maximum likelihood, and control function estimators, using parental indigenous language status as instruments. Unlike prior studies, we account for key confounders: parents' education, occupation, and imputed family income. SAL reduces education by one year—equivalent to a−0.2 standard deviations reduction on schooling. It also imposes a−23% penalty on permanent income (wealth). No significant effects are found on employment, life satisfaction, or health.