We investigate the effect of speaking Spanish at home as a child on completed schooling and aptitude test scores using data from the NLSY79 on Hispanics who grew up in the United States. We model the accumulation of traditional human capital and English fluency, leading to the joint determination of schooling and test scores. We find that speaking Spanish at home reduces test scores, but has no significant effect on completed schooling. The reduction in test scores (1) increases in magnitude in three of the tests when the parents are more educated; (2) is much more dramatic when the choice of home language is made endogenous; and (3) is not systematically greater for the verbal than for the math tests. (JEL I20, J15)