This study examines whether native and non-native speakers faced with unfamiliar formulaic expressions use the same tactics for working out what they mean. The test items needed to be semantically opaque, used in an authentic context and unknown to all participants. Ten obsolete expressions were selected from the historical novels of Georgette Heyer. First-language English speakers and UK-resident classroom-taught learners of English as a foreign language were individually presented with the expressions in their original context, and asked to work out what they meant. Analysis of their comments revealed that the native speakers deployed significantly more context and analogy. The non-native speakers were much more likely than native speakers to refer to individual unknown words. Whilst it seems that first-language users take a more holistic approach to linguistic input than classroom-taught second-language learners do, the findings may suggest that learners adopt increasingly 'nativelike' strategies as proficiency increases.