This study presents a cross-linguistic examination of reduplicative constructions in a sample of 120 Australian languages. It provides a descriptive and comparative analysis of these reduplications, using a cross-linguistic comparative methodology to clarify the role of reduplication in grammar. This is especially relevant to Australian languages since reduplication is largely used to express 'grammatical' rather than 'lexical' meaning. Chapter one provides an introduction to the aims and methods of the thesis. Chapter two discusses the phonological structure of reduplication in Australian languages by examining reduplication together with phonological parameters as phonological word boundaries and stress patterns. Chapter three characterises nominal reduplications and shows that reduplication of 'nouns' and 'adjectives' can be distinguished on a semantic basis, although formal grammatical differences between the two classes may rarely be evident in Australian languages. Chapter four examines the meanings which verbal reduplication may exhibit, and shows a correlation between the types of meanings found and the role of reduplication in verbal syntax semantics. The study concludes with a summary of the findings, some conclusions, and suggestions for further areas of study.