This study explores the acquisition of Spanish subject-verb inversion in wh-questions by Dutch L2 learners. The optional or obligatory application of this rule in Spanish wh-questions depends on the argument versus adjunct status of the wh-element. In Dutch, subject-verb inversionis obligatory in matrix clauses only and it is not subject to argumental restrictions. The empirical basis of this study comes from a Grammaticality Judgment Task offered to 46 participants: 33 Dutch learners of L2Spanish and 13 Spanish native controls. The results indicate that the L2ers' performance is significantly different from native-like behavior at two different levels of proficiency. (C) 2015 The Authors. Published by Elsevier Ltd.