This chapter is devoted to the functional variation of Left Marked Structures (LMSs) – namely, Left Dislocations (LDs) and Preposings (PRs) –, which are generally described as topic-marking discourse strategies. Results from a corpus-based and multi-level investigation demonstrate that in spoken and written Italian and English the claimed iconic relation between LMS’s syntactic form and information structure does not hold. Moreover, at the discourse level, LMSs impact not only the topical, but also the logico-semantic dimension of texts. The study proposes a reinterpretation of the general function of LDs and PRs in terms of textual prominence, showing how a corpus-based and multilevel analysis method could guide and in turn benefit from a typological investigation of LMSs’ inter- and intra-linguistic variation.