The purpose of this thesis is to examine hourly wage differences across different groups of Mexican-origin workers. First, I assess the cost of foreign-born status by comparing the hourly wages of Mexican immigrant workers with those of native-born Mexican American workers. Second, I assess the cost of non-citizenship status by comparing the hourly wages of non-citizens with those of Mexican-born U.S. naturalized citizens. I also seek to determine if these costs are greater in California than in Texas. The data are drawn from the 2000 5% Public Use Microdata Sample (PUMS) U.S. Census. The results from multiple linear regression analyses show that being an immigrant, particularly a non-citizen immigrant, is associated with lower hourly wages, especially in California. Thus, Mexicanorigin workers, especially those in California, bear dual costs for being foreign-born and not being naturalized citizens. Furthermore, I focus on length of U.S. residence to assess the social and economic impact of the different periods on the costs associated with foreign-born status. First, those who came to the United States before the IRCA of 1986 and a series of California propositions during the 1990s have higher hourly wages than those who arrived later, because of more stable labor market conditions and the effect of the duration of stay in the United States. Second, those who arrived during the last decade have much lower hourly wages because of their disadvantaged labor market contexts.