So far research on language acquisition has dealt mainly with the detection of acquisitional sequences disregarding functional overlapping and isolating levels of analysis (mainly morphology). This volume, relying on Costructionism and on authentic data, envisages the syntax acquisition as a network of constructions, where linguistic competence, syntactic complexity and functional proximity are globally considered, exploiting the network organization to describe the different acquisition patterns of complex constructions. The analysis of a 15 hours long L2 spoken Italian corpus leads on the one hand to confirm the acquisitional sequences proposed by the literature, and on the other to identify two fundamental acquisition processes: The integration of two propositions for the acquisition of coordinated and adverbial constructions, and expansion of one proposition for the acquisition of completive and restrictive relative constructions.