Tetun Dili is an Austronesian language spoken as a first language inDili, East Timor. It is also spoken as a lingua franca throughout much of this fledgling nation, and is set to become its national language. This grammar describes the basic structure of Tetun Dili, covering phonology and morphology, as well as phrase-, clause- and sentence-level syntax. It is based on a corpus of both spoken and written texts, supplemented by elicitation. While the focus is primarily on the spoken language, comparisons are made with both written and liturgical varieties. In contrast to the more conservative Tetun Terik variety, Tetun Dili shows strong Portuguese influence after centuries of contact, particularly in its lexicon and phonology. This work constitutes the most detailed grammatical description to date of any language of East Timor, complementing an earlier description of Tetun Terik as spoken in West Timor.