This article compares the use of discourse markers (DMs) in Italian as a second language (L2) produced by Belgian-Dutch learners, with the DMs produced by Italian native (L1) speakers. The quantitative analysis of the data shows that L1 speakers produce more DMs than L2 speakers, whereas the comparison between the levels of proficiency in L2 reveals an effect of the type of task on the frequency of DMs. From the qualitative analysis, interesting discrepancies emerge between the L1 and the L2 use of DMs, especially those uttered in sentence-internal position. We offer an analysis within the cartographic approach and we demonstrate that the sentence-internal DMs with an epistemic value realize specific syntactic positions dedicated to the expression of modality within the IP layer. We also show that the L2 learners, despite projecting the correct syntactic structure, realize it with pragmatically infelicitous forms as a result of linguistic interference with their L1. Our study brings original evidence on the syntactic status of DMs: given their multifunctionality, more syntactic options are available depending on the markers' discursive and pragmatic import. Furthermore, sentence-internal DMs reveal intriguing properties of the L2 acquisition at the syntax and discourse--pragmatics interface.