English, like all languages, typically involves a great variability in the duration of the structural units taken into account in the observation (phonemes, syllables, feet, words, etc.). In this paper some prosodic factors likely to influence the duration were tested for their influence in two analyses. In the first analysis, the predominant factor turned out to be the final position in the intonation unit. The second analysis takes a closer look at the influence of stress and accent and of the position in the intonation unit on the relative and absolute duration of each word.