By examining the acquisition of Spanish in combination with languages other than English (Arabic, Basque, Catalan, Chinese, Dutch, Farsi, French, German, Nahuatl, Quechua, Portuguese, Swedish, Turkish), this volume advances novel data pertinent to the field’s understanding of acquisition of Spanish in the XXI century. Its crosslinguistic nature invites to reconsider major theoretical questions such as the role of L1 transfer, linguistic typology, and onset of acquisition from a fresh perspective, and to question the validity of the traditional parameter (re)setting perspective taken in SLA. Additionally, this volume underscores the necessity of providing accurate descriptions of the language pairings investigated, emphasizing the interconnection between linguistic and SLA theory, and pushing to a more atomic view of the system in which features and feature bundles mapped onto lexical items comprise the skeleton of language.