611 Studies in Second Language Acquisition, 2014, 36, 611–645. doi:10.1017/S0272263113000727 © Cambridge University Press 2014 INCIDENTAL EXPOSURE AND L3 LEARNING OF MORPHOSYNTAX Sarah Grey Georgetown University John N. Williams University of Cambridge Patrick Rebuschat Lancaster University Evidence of learning following incidental exposure has been found for aspects of nonnative syntax in adults (Rebuschat & Williams, 2006, 2012; Williams & Kuribara, 2008). However, little research has tested delayed effects of learning under an incidental condition or moved beyond word order. This study investigated learning of third language (L3) morphosyntax (word order and case marking) under an inciden- tal exposure condition. Participants were second language Spanish learners exposed auditorily to a semiartificial language, Japlish, during a semantic plausibility judgment task. Performance following exposure to L3 Japlish was assessed with acceptability judgment and picture- matching tasks that were administered immediately after exposure and 2 weeks later. Results on immediate tests showed a significant learning effect on acceptability judgment but none for picture matching. At delayed testing, results showed maintenance of the learning effect on acceptability judgment and significantly improved performance on picture matching. Results additionally showed that many of the learners arrived at the correct Japlish word-order rule; fewer did so for case marking. Follow-up analyses indicated that this rule knowledge, Sarah Grey is now at Pennsylvania State University. The authors would like to thank three anonymous reviewers for their helpful feedback. Correspondence concerning this article should be addressed to Sarah Grey, Pennsylvania State University, Department of Psychology, 140 Bruce V. Moore Building, University Park, PA 16802. E-mail: seg24@psu.edu