This study attempts to tease apart the effect of dominant languages of communication on the acquisition of syntactic properties of L3 French in order to test the current L3 generative theories. Three groups of bilinguals took part in this study: L1 Persian/L2 English, with French as the dominant language of communication, L1 Persian/L2 English, with Persian as the dominant language of communication and L1 English/L2 Persian, with Persian as the dominant language of communication. English and French pattern similarly in the wh-question structures. That is to say, wh-question word moves pre-subject position while in Persian it remains "in situ." The results rejected the effect of the four proposals (e.g. the L1 factor; the L2 Status Factor; the Cumulative Enhancement Model [CEM]; the Typological Proximity Model [TPM]), but the role of dominant language) in the acquisition of the third language was confirmed by grammaticality judgment and element rearrangement task. The implication of this study suggests that the initial path of L3 acquisition is not determined by wholesale transfer or mixed transfer theories but rather by the learners' dominant language of communication.