Diachronic morphosyntacticians of all theoretical persuasions agree that there is a tendency for more lexical linguistic material to develop more functional characteristics over time, a process generally known as grammaticalization. While most previous work on grammaticalization has been conducted in surface-oriented functionalist frameworks, this dissertation aims to illuminate the deeper structural properties of a sub-set of these phenomena, diachronic affixation, as well as its much rarer opposite, de-affixation, a phenomenon in which previously bound material becomes a syntactically independent form. This approach differs from previous generative approaches to this problem in utilising a nonlexicalist, piece-based, syntactic approac...