This monograph presents a phonological model for the analysis of contextually determined variation in the realiziation of segments in spoken English. The data source for the analysis is the speech of post-intermediate Dutch learners of English. It is claimed that a satisfactory level of linguistic explanation for the form and position of such variants may be achieved by the postulation of a hierarchically ordered and internally differentiated model of suprasegmental phonological structure, which at the same time may serve as a tertium comparationis for the two languages in contact in the learning situation.