It has often been observed that sentences such as (1) are ambiguous: (1) Mary has lived in Amsterdam for three years. Sentence (1) has a reading in which there is some three-year interval in the past during which Mary lived in Amsterdam, and a reading in which Mary lives in Amsterdam at speech time and has done so for the three years preceding speech time. I will argue that this ambiguity is also present in sentences in the simple tenses, and that a unified treatment of for (as well as other temporal adverbials) is possible once it is recognised that temporal adverbials are interpreted differently depending on their syntactic position. Rather than attributing the ambiguity of such sentences to lexical ambiguity of the adverbial, I argue that the interpretation of a sentence with a temporal adverbial is affected by the partition of the sentence into two portions which are interpreted as parts of different semantic correlates, much like Topic/ Comment and Background/Focus constructions.