Although governments worldwide are increasingly choosing to deliver services through organisations with greater autonomy than traditional bureaus, the implicit assumption that such agencification contributes to long-run efficiency remains largely untested. Agencification gives agency managers more autonomy and access to incentive mechanisms that lead to greater efficiency if they are not offset by inefficiencies resulting from managerial discretion. We test the hypothesis that agencification improves efficiency by examining the longer-run performance of 13 agencies in the province of Québec, Canada over approximately 10 years. We find that these agencies experienced long-term productivity gains, but that these gains reached a plateau over the time period studied. In addition, we describe changes in several measures of performance. A survey of the managers of these agencies indicates that they perceive agencification as having a substantive impact, but worry about the sustainability of autonomy and their capacity to show continued gains in measured performance over time.