The research on urban leadership attributes the performance of mayors either to institutional factors or to individual characteristics. Taking advantage of a 'natural experiment', we assess the effects of a change from a commission to a mayor-council government on an individual who served as mayor in both. Using data from personal interviews, we compare the roles attributed to the incumbent and find the roles emphasised shifted with the change in structure. We also found that the mayor's leadership style did not change, suggesting that the change in structure accounts for the differences in reported activities.