The Network for the Improvement of Addiction Treatment (NIATx) applies process improvement strategies to enhance the quality of care for the treatment of alcohol and drug disorders. A prior analysis reported significant reductions in days to treatment and significant increases in retention in care [McCarty, D., Gustafson, D. H., Wisdom, J. P., Ford, J., Choi, D., Molfenter, T., Capoccia, V., Cotter, F. 2007. The Network for the Improvement of Addiction Treatment (NIATx): enhancing access and retention. Drug Alcohol Depend. 88, 138-145]. A second cohort of outpatient (n=10) and intensive outpatient (n=4) treatment centers tested the replicability of the NIATx model. An additional 20 months of data from the original cohort (7 outpatient, 4 intensive outpatient, and 4 residential treatment centers) assessed long-term sustainability. The replication analysis found a 38% reduction in days to treatment (30.7 to 19.4 days) during an 18-month intervention. Retention in care improved 13% from the first to second session of care (from 75.4% to 85.0%), 12% between the first and third session of care (69.2-77.7%), and 18% between the first and fourth session of care (57.1-67.5%). The sustainability analysis suggested that treatment centers maintained the reductions in days to treatment and the enhanced retention in care. Replication of the NIATx improvements in a second cohort of treatment centers increases confidence in the application of process improvements to treatment for alcohol and drug disorders. The ability to sustain the gains after project awards were exhausted suggests that participating programs institutionalized the organizational changes that led to the enhanced performance.