Project IMPACT is a collaborative care intervention to assist older adults suffering from major depressive disorder or dysthymia. Qualitative research methods were used to determine the barriers and facilitators to sustaining IMPACT in a primary care setting. Strong evidence supports the program's sustainability, but considerable variation exists in continuation strategies and operationalization across sites. Sustainability depended on the organizations' support of collaborative care models, the availability of staff trained in the intervention, and funding. The intervention's success was the most important sustainability factor, as documented by outcome data and through the "real world" experience of treating patients with this intervention.