The article describes the properties of deverbal nouns (maṣdars) in Standard Arabic. Prior accounts identify the following type (qaṣfu l-ʿaduwwi li-l-madīnati), among others, but neglect the maṣdar that introduces its internal argument as a direct complement in the genitive case and its external argument as a prepositional adjunct (taḥrīru l-madīnati ʿalā yadi l-jayši ). We argue that these two types reflect two different conceptu-alizations of ‘events’: bound-events, which describe a change that has taken place in the nature of a sub-stance represented by the internal argument; and unbound-events, which describe a change in the relation-ship between the internal and external arguments.Within the lexical decomposition model, we propose a semantic basis for explaining constraints on direct transitive verbs according to (i) the type of maṣdars they form; (ii) the possibility of deriving a resul-tative passive participle (ism al-mafʿūl); and (iii) the alternation, for some verbs, between a causative and non-causative use without any morphological variation.Keywords: lexical decomposition, deverbal noun (maṣdars), (un)bound-event