The experiments tested whether structural priming within a language differs from priming between languages and whether priming between a first and second language differs from priming between two different second languages.Experiment 1 tested priming of relative clause attachment from Dutch (the subjects' first language), French, or English (two second languages) to Dutch. Experiments 2 and 3 were similar but had respectively French and English as the target language. Experiment 4 tested dative priming from Dutch, English, and German (another second language) to English. Structural priming was always as strong within-as between-languages and priming between a first and a second language was always as strong as priming between two second languages. These findings support accounts that assume syntax is shared across languages.Keywords: Bilingualism; Multilingualism; Structural Priming; Sentence Production multilingual cross-linguistic priming 3 Worldwide it is the rule rather than the exception that people speak more than one language (Graddol, 2004;Grosjean, 1992); in some parts of the world most people even speak more than two languages. For instance, most people from the region of Flanders, Belgium, have Dutch as their first language (L1), but also know French, English and sometimes German as a second language (L2) 1 , which they typically started to learn towards the end of primary school, at the beginning of secondary school, and in the last years of secondary school respectively. Many studies on bilingualism have asked whether there are influences of L1 on processing an L2 (e.g., Thierry & Wu, 2007) or vice versa (e.g., Van Assche, Drieghe, Duyck, & Hartsuiker, 2009). Fewer studies have considered cross-language influences in speakers of more than two languages. However, multilingualism offers the possibility of comparing cross-linguistic influences between a first and second language with influences between two different second languages (see Lemhöfer, Dijkstra, & Michel, 2004;Van Hell & Dijkstra, 2002 for such studies in the lexical domain). This article will present such a comparison in the domain of sentence production in order to arbitrate between theories that assume syntactic representations are shared or separate across a multilingual's languages. Although most cognitive-psychological studies on multilingualism have focused on the representation or processing of words, there is an increasing interest in research on syntactic processes in bilingual sentence production (e.g., Hartsuiker, Pickering, & Veltkamp, 2004;Kootstra, Van Hell, & Dijkstra, 2010;Loebell & Bock, 2003; Meyer & Fox Tree, 2003). Most of these studies use the structural priming paradigm, which is based on the phenomenon that the choice out of two alternative syntactic structures (e.g., an active instead of a passive multilingual cross-linguistic priming 4 sentence) is influenced by having recently processed a prime sentence with that specific structure (Bock, 1986). In a series of seminal studies, Bock and colleagues ruled out that st...