Syntactic persistence is a tendency for speakers to reproduce sentence structures independently of accompanying meanings, words, or sounds. The memory mechanisms behind syntactic persistence are not fully understood. Though some properties of syntactic persistence suggest a role for procedural memory, current evidence suggests that procedural memory (unlike declarative memory) does not maintain the abstract, relational features that are inherent to syntactic structures. To evaluate the contribution of procedural memory to syntactic persistence, patients with anterograde amnesia and matched control speakers (a) reproduced prime sentences with different syntactic structures; (b) reproduced 0, 1, 6, or 10 neutral sentences; (c) described pictures that elicited the primed structures spontaneously; and (d) made recognition judgments for the prime sentences. Amnesic and control speakers showed significant and equivalent syntactic persistence, despite the amnesic speakers' profoundly impaired recognition memory for primes. Syntax is thus maintained by procedural memory mechanisms, revealing that procedural memory is capable of supporting abstract, relational knowledge.Speakers often produce sentences using syntactic structures that they have recently spoken or heard. For example, speakers who produce or understand a sentence with a prepositional dative structure like "The governess made a pot of tea for the princess" are prone to describe a subsequent unrelated event with another prepositional dative structure, like "The boy is handing the paintbrush to a man." But if speakers initially produce or understand a sentence with a double-object structure like "The governess made the princess a pot of tea," they are more likely to describe the subsequent event with another double-object structure, like "The boy handed the man the paintbrush."This effect is known as syntactic persistence or structural or syntactic priming (for recent reviews, see Ferreira & Bock, 2006; Pickering & Ferreira, in press). Syntactic persistence has been observed in laboratory settings (Bock, 1986), controlled dialogue (Branigan, Pickering, & Cleland, 2000), natural discourse (Szmrecsanyi, 2004(Szmrecsanyi, , 2005, in different languages (Hartsuiker & Kolk, 1998b) and modalities (Cleland & Pickering, 2006), in children (Huttenlocher, Vasilyeva, & Shimpi, 2004; Thothathiri & Snedeker, in press), and even from one of a bilingual speaker's languages to the other (Hartsuiker, Pickering, & Veltkamp, 2004;Loebell & Bock, 2003). In certain paradigms (including the one used here), syntactic persistence is sensitive specifically to syntactic structure, rather than conceptual, lexical, or phonological information (Bock, 1986(Bock, , 1989Bock & Loebell, 1990;Bock, Loebell, & Morey, 1992 Syntactic persistence reflects memory for abstract syntax, because a prime sentence can only influence target production when some trace of the prime's syntactic structure is preserved in memory. However, the nature of the memory processes that underlie syntactic persi...