In this paper we propose the codification of argument and event structures in wordnets, providing information on selection properties, semantic incorporation phenomena and internal properties of events, in what we claim to be an affordable procedure. We propose an explicit expression of argument structure, including default and shadow arguments, through three new relations and a new order feature. As synsets in wordnets are associated to a given POS, information on the selection properties of lexical items is added. We show that the systematic encoding of event structure information, through five new features at synset level, besides providing the grounds for describing the order of arguments, enriches the descriptive power of these resources. In doing so, we crucially contribute to making wordnets rich and structured repositories of lexical semantic information, that allow for the extraction of argument and event structures of lexical items, thus enhancing their usability in NLP syste...