This study investigated the acquisition of Spanish Differential Object Marking (DOM) by bilingual and monolingual Spanish teenagers, evaluating to which extent their knowledge of DOM can be explained by different theories of acquisition.

Two experiments with bilingual and monolingual Spanish teenagers (ages 10 to 15) were conducted. The experiments included an Elicited Production Completion Task, in which a space was to either be filled with an object marker or left blank, and a Context-Matching Acceptability Judgment Task.

54 subjects (44 bilinguals and 10 monolinguals) were tested. For both tasks, there were 6 conditions testing different syntactic–semantic features that trigger DOM (test items n = 42 in each task). The data were analysed with linear regressions and repeated measures analyses of variance.

This study’s results show that bilingual teenagers do not demonstrate significant differences from age-matched monolinguals in their competence regarding the syntactic–semantic properties of DOM. Both groups are below ceiling in showing evidence of knowledge about all the syntactic–semantic features involved in DOM, indicating the possibility of a significant delay beyond childhood in their acquisition.

There are few previous studies on the acquisition of DOM, and none which consider the full range of features and specific population considered here. Work by Montrul focuses on the animacy feature, while Guijarro-Fuentes considers the full range of features, but for adult L2 learners of Spanish.

This study shows that the Interface Vulnerability Hypothesis, the Feature Reassembly Hypothesis, the Full Access/Full Transfer Hypothesis and the Interpretability Hypothesis have limitations in explaining its results. Instead, a feature-based approach is proposed in which the specification of features beyond animacy raises difficulties for the acquisition of DOM until late childhood.