The present study investigated L1 transfer effects in L2 sentence processing and syntactic priming through comprehension in speakers of German and Italian. L1 and L2 speakers of both languages participated in a syntactic priming experiment that aimed to shift their preferred interpretation of ambiguous relative clause constructions. The results suggested that L1 transfer affects L2 processing but not the strength of structural priming, and therefore does not hinder the acquisition of L2 parsing strategies. We also report evidence that structural priming through comprehension can persist in L1 and L2 speakers over an experimental phase without further exposure to primes. Finally, we observed that priming can occur for what are essentially novel form-meaning pairings for L2 learners, suggesting that adult learners can rapidly associate existing forms with new meanings.