Data-driven campaigning is often depicted as the latest iteration of modern campaign practice. This term captures the idea that political parties now routinely gather data from online and offline sources to inform decision making in regard to a range of campaign actions. Within existing scholarship, however, comparative studies of campaign practice are lacking, meaning that we lack an understanding of how and why data-driven campaigns vary across different contexts. In this paper we offer an in-depth analysis of data-driven campaigning in two European countries; Austria and the UK. Using elite interviews with party officials and campaigners in nine parties, we conduct a qualitative thematic analysis to explore data-driven campaigning practices and perceptions. Through this research, we highlight hitherto unappreciated cross-national variations in data-driven campaigning and suggest that differences can be attributed to structural and agential factors.