In Hebrew, European-Portuguese, Spanish, and Palestinian-Arabic both SV and VS orders are possible. In the early stages of sentence construction, however, children acquiring these languages do not use the whole array of word orders in their language. Their word order preference differs in the different languages: in the first stage, Hebrew and European-Portuguese children use both SV and VS orders with unaccusative verbs, but only SV with unergative and transitive verbs. In Spanish and Palestinian-Arabic, on the other hand, children prefer VS order with unaccusative, unergative, and transitive verbs. We propose an account according to which children at this stage cannot move the subject outside of VP yet, and the cross-linguistic difference stems from the identification of Spell-Out Domains (Fox & Pesetsky 2004a). Spanish and Palestinian-Arabic allow the verb to appear before the subject, whereas Hebrew and European-Portuguese do not allow the verb to move to I until the Spell-Out domain widens beyond VP, which takes place after subject movement to Spec,IP is acquired.