This study examines the labor market costs associated with being foreign-born and not having U.S. citizenship among Mexicans in California and Texas, the two largest states. Data from the 2000 5% Public Use Microdata Sample are used to conduct the multivariate regression analysis. The results show that being an immigrant, particularly a non-citizen immigrant, is associated with lower hourly wages in California as compared with Texas. The results also indicate that these costs are greater for those who arrived after 1990, especially in California. Findings suggest that Mexican immigrants faced harsher social context in California in the post-IRCA (Immigration Reform and Control Act) period, as represented in anti-immigrant policies and sentiments. Partly, larger population concentration of immigrants, especially non-citizens, could be a source of intensive within-group labor market competition among the foreign-born workers. (Contains 6 tables and 11 notes.)