The present study examines whether, as proposed by the Interface Hypothesis (Sorace, 2011), the syntax-discourse interface is especially vulnerable to non-native optionality even at very advanced levels. I focus on the acquisition of Clitic Left Dislocation in Spanish (CLLD), a structure that involves both syntax and discourse, when it combines with other structures at the left periphery (iterative topics, Fronted Focus, and wh-constructions). CLLD is a realization of topicalization requiring the integration of syntactic and discourse knowledge. This study provides data from an audio-visual rating task completed by 120 learners of Spanish of different proficiency levels and 27 monolingual native speakers. Results showed evidence that the most advanced learners had acquired the restrictions of these structures in a native-like way and supports López’s (2009) syntactic analysis of CLLD, whereby CLLD is generated through movement so that the pragmatic features [+anaphor]/[+contrast] can be assigned to the dislocated element.