Book excerpt: Using data from a variety of languages, this book investigates the place of clitics in the theory of language structure, and their implications for the relationships between syntax, morphology and phonology. It is argued that the least powerful theory of language requires us to recognise at least two classes of clitics, one with the syntax of independent phrases and the other with the syntax of inflectional affixes. It is also argued that prosodic conditions may influence the surface position of clitics beyond what may be accomplished by filtering potential syntactic structures. Finally, the relationship between syntactic, morphological, and phonological constituents within wordlike elements is explored.