This thesis investigates the intonation system of Anglesey Welsh, an under researched variety with regards to its suprasegmental aspects. The main aim of this thesis is to provide a fine-grained intonational investigation into the realisation of the structural components of the intonation system. The secondary aim considers a functional hypothesis proposed by Haan (2002), that there may be a trade-off between the amount of lexicosyntactic marking used to cue interrogativity (e.g. inversion, wh-words) and the amount of intonational marking (e.g. higher and later accent peaks). With regards to the phonetic realisation of the structural elements, two features are investigated: the vertical scaling (or height) and the temporal alignment to the segmental string. The materials were manipulated to test the effect that a) grammatical function and b) temporal constraints had on the scaling and alignment of the structural components. The results show that the scaling (height) was significantly affected by the grammatical function of the test sentences, with the structural components in questions being realised higher than statements. With regards to alignment, there was evidence of significant adjustments in the location of some structural components as a function of the number of syllables available in the sentence. The final part of this thesis discusses issues surrounding a phonological analysis of the intonation system using the scaling and alignment data. It is proposed that Anglesey Welsh questions and statements are best analysed as having a rising L+H* in both prenuclear and nuclear position, followed by a low boundary tone L%. This thesis contributes to knowledge on prosodic typology by analysing the structure and function of the intonation system using a widely used approach to intonational analysis (the autosegmental-metrical approach). Furthermore, it tests questions about the phonetic implementation of intonation in Anglesey Welsh and uses the patterning to discuss an appropriate underlying phonological representation of the intonation.