Negation has been researched in second language acquisition in several languages (Bernini 2000; Donaldson 2017; Eskildsen 2012). However, there are very few studies that have discussed the acquisition of negation in L2 Spanish. In Alexandrino's (2010) dissertation, Grammaticality Judgment Tasks are employed to indicate that the acquisition of negative concord in Spanish is more successfully achieved by L1 Portuguese-speaking learners than by L1 English-speaking learners, suggesting that L1 Transfer is a relevant factor in the development of target-like negative concord in L2 Spanish. However, further research is needed to understand the difficulties that L1 English-speaking learners face when learning negative concord in Spanish. In order to fill this gap in the literature, the present study measures the acquisition of negative concord in L2 Spanish among 94 English-native learners enrolled in university Spanish language courses. Two structured oral production tasks were designed to elicit negative concord constructions, focusing on both word order and lexical semantics. In the first task, participants must orally complete dehydrated sentences that correspond to given prompt images, which test whether or not they will produce a preverbal negation "no" in phrases that feature postverbal negative polarity items "nada" and "nadie." In the second task, participants complete a similar task, but are also prompted to answer questions featuring positive polarity items "algo" and "alguien," by producing responses with negative polarity items "nada" and "nadie." Results indicate that learners produce negative concord structures more accurately with greater proficiency, and that they develop the word order concordance between negative items before developing the polarity-based semantics of lexical negative items. These results are accounted for in terms of Filipovic and Hawkins' Complex Adaptive Systems Principles (CASP) model of SLA (Filipovic and Hawkins 2013). [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]