This paper examines the relationship that exists between the syntactic and phonological components of the transformational-generative model insofar as their formal structures are concerned. It is demonstrated that the number and importance of the structural similarities between the syntax and the phonology make it necessary to provide for them in the theory. The author suggests this be done by showing that underlying the two components of the grammar there is a single unified structure, with a generative capacity embodied in a set of string-structure rules and a further set of transformational rules converting a deep level of representation to a surface representation and embodying such phenomena as neutralization, ordering, cycling, and other properties. (RL)