This dissertation investigates the neural and behavioral correlates of grammatical agreement computation during language comprehension in native English speakers and highly advanced L1 Spanish-L2 English bilinguals. In a series of electrophysiological (event-related brain potential (ERP)) and behavioral (acceptability judgment and self-paced reading) experiments, I argue that grammatical dependency creation between discontinuous items is subserved by a general content-addressable memory mechanism, and moreover, that fundamentally similar mechanisms operate during native and nonnative language processing. More specifically, I use the "agreement attraction" paradigm to show that proper integration of subject-verb agreement in native speakers is subject to interference from nouns that cannot syntactically license agreement (i.e., a classic attraction effect), but that interference during first-pass parses is asymmetrical. Attractor nouns mitigate ungrammaticality effects for disagreeing verbs, but do not increase difficulty integrating grammatical verbs. Attraction in grammatical sentences occurs, but only during sentence-final wrap-up processes. I show additionally that interference from attractor nouns is subject to linear, time-based decay, and furthermore, that attraction interference in comprehension is not clause-bound, as has been shown to be the case during production. Instead, clausal effects were shown to facilitate the retrievability of matrix clause verbs in general, and that this did not interact with agreement properties of the verbs themselves. Results for second language (L2) learners largely paralleled those for native speakers. Highly advanced native Spanish learners of L2 English showed similar profiles of attraction interference and similar clausal facilitation effects. This result is incompatible with recent claims that L2 processing is restricted shallow, linear or thematic heuristics, and instead supports the claim that similar cognitive and neurocognitive mechanisms support native and L2 processing at high levels of L2 proficiency. Finally, regression analyses on L2 learners' brain responses additionally showed that a substantial proportion of the variance in the type of individuals' ERP responses to subject-verb agreement violations (N400 or P600) could be accounted for by a coalition of individual-level variables, with the most robust predictor of brain responses being subjective importance to sound like a native English speaker. [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/en-US/products/dissertations/individuals.shtml.]