AbstractIn Jackendoff's Parallel Architecture, the well‐formed expressions of a language are licensed by correspondences between phonology, syntax, and conceptual structure. I show how this architecture can be used to make sense of the existence of parasitic gap constructions. A parasitic gap is one that is rendered acceptable because of the presence of another gap in the same sentence. Compare *a person whoeveryone who talks tolikes Chris, which shows an illicit extraction from a relative clause, anda personeveryone who talks tolikes, which shows a parasitic gap in the relative clause. Languages differ in terms of the range of configurations in which they allow parasitic gaps; these configurations appear to form a hierarchy.These observations raise some fundamental questions:Why do parasitic gaps exist at all?Why are different syntactic configurations possible for P‐gaps and why just these configurations?Why is there a parasitic gap hierarchy?The answers that I propose make crucial use of constructional overgeneralization of across‐the‐board extraction in coordinate constructions, formulated straightforwardly in the framework of Jackendoff's Parallel Architecture.