In the light of neoinstitutional theory and by adopting case study research methodology, this article explains the adoption of International Public Sector Accounting Standards for modernizing public sector accounting in Estonia. This article reveals that the smoothyet gradualadoption of International Public Sector Accounting Standards-compliant accounting systems was enabled by the involvement of powerful actors (i.e., institutional entrepreneurs) with foreign and/or business backgrounds. In addition, the change in public sector accounting in Estonia was facilitated by the developments in its international positioning, characterized by the transition from a Soviet communist to a market economy and subsequent European Union membership and by the absence of past accounting practices, which could potentially hinder the change.