The most productive way to encode ablative, privative, and reversative meanings in current Catalan and Spanish is by means of des- prefixation. This paper investigates how these related values are obtained both from a structural and from a conceptual perspective. To analyze the structural behaviour of these predicates, a new neo-constructionist model is adopted: Nanosyntax, according to which lexical items are syntactic constructs. As for the conceptual content associated to these verbs, it is accounted for by means of a non-canonical approach to the Generative Lexicon Theory developed by Pustejovsky (1995 ff.).The core proposal is that des- prefixed verbs with an ablative, a privative, or a reversative meaning share the same syntactic structure, and that the different interpretation of each semantic class emerges as a consequence of the interactions generated, at a conceptual level, between the Qualia Structure of the verbal root and that of the internal argument of the verb.