This article utilises large-N panel data to compare two theories of referendum voting behaviour in order to understand the ‘for’ or ‘against’ vote in the 2016 Dutch referendum on the EU-Ukraine Association Agreement. It studies the extent to which voting behaviour was predicted by Eurosceptic attitudes and fear of upsetting Russia (issue-based theory), versus dissatisfaction with the Dutch government and general political discontent (second-order theory). Our findings indicate that issue-based determinants predict the referendum vote better than second-order predictors. However, Eurosceptic attitudes and government satisfaction both outperform concerns about the relationship with Russia as a predictor. We thus provide evidence that the issue-based and second-order approaches to explain voting in EU referendums are complementary, but not equal in explanatory strength. ...