This article reports on a corpus stylistic study of the language of soliloquies in Shakespeare’s plays. Literary corpus stylistics can use corpus linguistic methods to test claims made by literary critics and identify hitherto unnoticed features. Existing literary studies of soliloquies tend to define and classify them, to trace the history of the form or to offer literary appreciation; yet they pay surprisingly little attention to the language which characterises soliloquies. By creating a soliloquy corpus and a dialogue corpus from 37 Shakespeare plays, and comparing the former against the latter using WordSmith Tools, I identify key language forms in soliloquies. Using an analytical framework broadly based on Halliday’s ideational, interpersonal and textual metafunctions of language, I interpret my results and relate them, where possible, to literary critical interpretations. I also compare comedy, history and tragedy soliloquy corpora. My main findings show the following linguistic features to be characteristic of soliloquies in general: words relating to mental states and the body; pragmatic noise; linking adverbials and first-person pronouns. Characteristic forms in comedy, history and tragedy emphasise love, the monarch and the supernatural respectively. The empirical evidence presented here shows that Shakespeare regularly exploited certain language forms in soliloquies to represent expressions of doubt, resolve, introspection and strong emotion, among others. These forms not only add depth to characterisation, aid plot development and provide performance cues for actors, but may also conform to certain audience expectations.