The size and composition of general government employment can vary significantly amongst OECD-EU countries for various reasons. Workforces reflect different government models in terms of the functions their civil services carry out and how they are centralised or decentralised. However, aside from these inherent characteristics, there are differences arising from how general government employment is defined and measured. Some countries collect data through civil service registries, payroll or other human resources management administrative databases, while others draw data from national labour force surveys or other sources. Data are often not centralised and/or harmonised across government. There are also differences in how countries classify public employees. All of these factors can hinder international comparison as well as the design of evidence-informed public employment practices and reforms. This paper, with support from the European Commission, aims to improve the availability, granularity, and comparability of public employment data by mapping existing data sources, gaps, and methodological approaches.