Experimental studies have robustly demonstrated the effectiveness of the Individualized Placement and Support (IPS) model of supported employment services for people with severe mental illness, and several studies of real-world implementation have shown significant cross-sectional correlations between employment success and fidelity to the IPS model. Experiences with IPS programs have stimulated broad efforts to disseminate evidence-based practices. Although multiple dissemination efforts are underway, analyses on the benefits of efforts to disseminate IPS have been on cross-sectional and site-level data, rather than on longitudinal information on individual clients. To implement IPS in health care systems with limited previous experience, sustained and individualized training programs may be needed to realize potential client benefits. Few studies have demonstrated that IPS, or other evidence-based practices for that matter, can both be implemented in a system that lacks prior experience with the model and yield outcomes for comparable cohorts that are superior, over several years, to those of a comparison group for which this intervention was not available.