To improve the geographic distribution of physician assistants and nurse practitioners in California, the Primary Care Associate Program established five community-based training sites in outlying areas while continuing to operate its core program within the San Francisco Bay Area. To evaluate this effort, the authors prospectively compared the employment locations of graduates from both groups, achieving a follow-up rate of 95%. Graduates from community sites were twice as likely to locate first practices outside the Bay Area (91% vs. 43%, P less than 0.05) and in towns with less than 10,000 inhabitants (33% vs. 16%, P less than 0.05). Over the decade, the percentage of graduates practicing outside the Bay Area rose from 0 to 9% for trainees both recruited from and entirely trained within the Bay Area versus 76-84 percent for trainees experiencing any element of decentralization. The slopes of these two lines represent the effect of the increasing supply of graduates on practice location away from Stanford (9%); the distance between the lines, the greater effect of decentralization (73%). Given the goal of statewide deployment of a small number of graduates, decentralization appears to have been an effective approach.