MWE 2013 will be the 9th event in the series. We will be interested in major challenges in the overall process of MWE treatment, both from the theoretical and the computational viewpoint, focusing on original research related (but not limited) to the following topics: Manually and automatically constructed resources; Representation of MWEs in dictionaries and ontologies; MWEs in linguistic theories like HPSG, LFG and minimalism; MWEs and user interaction; Multilingual acquisition; Multilingualism and MWE processing; Models of first and second language acquisition of MWEs; Crosslinguistic studies on MWEs; The role of MWEs in the domain adaptation of parsers; Integration of MWEs into NLP applications; and Evaluation of MWE treatment techniques; Lexical, syntactic or semantic aspects of MWEs.