This article investigates the syntactic and semantic properties of complex predicates in Persian in order to isolate the individual contributions of the verbal components. The event structure of causative alternation and unergative verbs is determined, based on a decomposition of the verbal construction into primitive syntactic elements consisting of lexical roots and functional heads, with the latter projecting all arguments of the verbal construction. An analysis is provided whereby the argument structure is not projected from the lexicon but is formed compositionally by the conjunction of the primitive components of the complex predicate in syntax. The dual behaviour of Persian complex predicates as lexical and syntactic elements, which has been attested in Persian literature on light verb constructions, follows naturally from the analysis proposed since there is no strict division between the level of word formation and the component manipulating phrasal constructs.