Purpose
As a result of public budgeting reform, the concept of performance has been integrated into budgeting practices in Cambodia for more than ten years. However, the effectiveness of the reform in improving public services is still limited. Drawing on the limited impact of the reform, this study examines the forces that drive (or hinder) performance budgeting reform in Cambodia.

Design/methodology/approach
To achieve the purpose of the study, Pollitt and Bouckaerts model of public management reform was used as the theoretical framework, and a qualitative research design was adopted to guide the research process. Data was collected between late 2019 and early 2020, and the data sources were documents and semi-structured interviews with key stakeholders in the reform process.

Findings
Pollitt and Bouckaerts model categorises reform forces into four broad categories: socio-economic forces, political forces, administrative forces, and chance events. Through the lens of the model, the study identified that political forces and socio-economic forces contribute to the start and continuation of performance budgeting reform in Cambodia, but administrative forces appear to delay the reform. The study identified three administrative challenges: (a) the limited capacity of the information and technology system; (b) the limited capacity and capability of officials; and (c) competition for control. In terms of chance events, the study could not find evidence of their presence in the available data.

Originality
A key contribution of this study is the understanding of how performance budgeting reform was initiated and implemented in Cambodia, a developing country with specific historical and political contexts. Thereby, enabling potential solutions to the reforms limited effectiveness.