Research in Second Language Acquisition (SLA) has studied negation in a wide variety of languages but has mainly focused on the acquisition of clause negation, or the negation of finite verbs in main clauses (Dimroth, Christine. 2008. Age effects on the process of L2 acquisition? Evidence from the acquisition of negation and finiteness in L2 German. Language Learning 58(1). 117–150). The present study discusses the acquisition of negative concord (NC) in L2 Spanish, from both a syntactic and a lexical approach to the analysis of learner production data. The results of a structured oral elicitation task indicate that learners produce NC with the negative concord items (NCIs) nada ‘nothing’ and nadie ‘no one’ in argument position, and also ascertain their appropriate usage contexts, with greater accuracy as their L2 proficiency increases. These findings are discussed in relation to studies of NC in English and English First Language Acquisition (FLA), and also to recent work in English SLA on the acquisition of negative polarity items (NPIs) (Gil, Kook-Hee, Heather Marsden & Melinda Whong. 2019. The meaning of negation in the second language classroom: Evidence from ‘any. Language Teaching Research 23(2). 218–236; Marsden, Heather, Melinda Whong & Kook-Hee Gil. 2018. What’s in the textbook and what’s in the mind: Polarity item “Any” in learner English. Studies in Second Language Acquisition 40(1). 91–118; Puig-Mayenco, Eloi & Heather Marsden. 2018. Polarity-item “anything” in L3 English: Where does transfer come from when the L1 is Catalan and the L2 is Spanish? Second Language Research 34(4). 487–515). Ultimately, this study aims to contribute to further research in the literature on complex negation constructions in SLA and underline the interplay of syntactic, semantic, and lexical issues in the acquisition of these structures.