This article employs a unique method of inferring the legal status of Mexican immigrants in the Survey of Income and Program Participation to offer new evidence of the role of legal authorization in the United States on workers' wages. We estimate wage trajectories for four groups: documented Mexican immigrants, undocumented Mexican immigrants, U.S-born Mexican Americans and native non-Latino whites. Our estimates reveal a gross 17 percent wage disparity between documented and undocumented Mexican immigrant men, and a 9 percent documented-undocumented wage disparity for Mexican immigrant women. When worker human capital and occupation are held constant, these wage gaps reduce to 8 and 4 percent, respectively. We also find large differences in returns to human capital with undocumented Mexican immigrants having the lowest wage returns to human capital and having very slow wage growth over time. (Contains 5 notes and 6 tables.)