Actually and in fact have been generally regarded as interchangeable without leading to any significant differences in the meaning of the containing utterances: as a result, no serious attempt has been made to discover potential differences between the two. The present study focuses on the differences as well as the similarities between actually and in fact in their distribution and use in spoken and written American English. Based upon an analysis of tokens from the Switchboard Corpus and the Brown Corpus, I propose that `unexpectedness’ is the core meaning shared by actually and in fact, and that the difference between the two lies in the typical association of each with one or the other way of signalling ‘unexpectedness’. The study also shows that in real discourse contexts, actually and in fact develop a number of different uses that are more or less remote from this core meaning.