The present study follows the role of the first (L1, English) and second (L2, Japanese or Spanish) languages in ab initio third language (L3, Latin) acquisition. Participants (N = 25) were L2 classroom learners without immersion experience. In order to complement previous generativist studies and to offer a fuller developmental account of how transfer operates at the morphosyntactic level, the Competition Model (CM) was adopted as theoretical framework. Positive changes in overall accuracy and sentence processing patterns in role assignment in L3 Latin show L3 development as largely modulated by the L1, suggesting that higher levels of L2 resonance are necessary for integrated patterns of L1 and L2 cues to emerge.
