The objective of this study was to use administrative data to examine the effect of drug treatment completion on patients' subsequent employment and wages earned in the year following discharge, and to compare the consistency of these results across three states. Drug treatment and wage data from 20,495 drug treatment patients were used in this study. Treatment data were provided by the state substance abuse management information systems for Baltimore City, Washington State, and Oklahoma. Wage data were provided by the agency in each state responsible for collecting and reporting wage information. A quasi-experimental design was used to compare treatment completers and non-completers in the year after an index treatment episode. In addition, employment history in the year prior to the index episode was used to statistically adjust for group differences. The index episode of care may have included services under more than one treatment modality. The full social security number was used to link the drug treatment and wage administrative datasets. Treatment completers were 22% to 49% more likely than non-completers to be employed and to earn higher wages in the year following treatment, holding other variables constant. Patients staying in treatment longer than 90 days were 22% to 43% more likely to be employed in the year following treatment than those who stayed a shorter time. These findings were consistent across the three project states with different client populations, treatment delivery systems, and labor markets.