Recent years have seen a strong growth in comparative public administration research. In Europe, increasing integration has stimulated interest in comparative studies of European countries’ administrative systems and how these are changing. There has also been a strong increase in the empirical material available for comparative analysis. Much of this material comes from international organisations, but also researchers have compiled large empirical datasets, building on a tradition of administrative elite studies. The COCOPS project has been developed as one of the largest comparative research projects in Europe ever. Its objectives are to advance the study of the transformations of European administrative systems by taking a broader perspective on public management and administrative reforms, by setting up a systematically comparative research design and by constructing an original dataset based on a large-scale executive survey. This chapter introduces the multi-country COCOPS Top Public Executive Survey, including the sample and the questionnaire.