This dissertation aims to identify the locus of L2 processing inefficiency. Previous studies suggest that non-native processing is a specific result of an inefficient predictive mechanism that limits the ability of learners to generate linguistic expectations (Gruter, Rohde, & Schafer, 2014; 2016). Thus, this study employs two distinct online sentence processing tasks to disentangle processing mechanisms at the level of integration and prediction and to evaluate the effects of L2 linguistic knowledge and resource limitations on anticipatory processing of morphosyntax. Native Spanish-speakers ( n = 32) and native English-speaking learners of Spanish at intermediate and advanced levels (n = 67) completed a picture-selection task and a self-paced reading task. The former isolates predictive mechanisms by testing the learners' ability to utilize number cues to anticipate upcoming constituents and the latter measures learners' sensitivity to number violations. Factors related to cognitive and language experience were also examined via tasks which measured working memory, lexical automaticity, verbal fluency, proficiency, vocabulary size, and metalinguistic awareness. The findings revealed that all learners are able to detect grammatical violations while reading, but only advanced learners are able to utilize number morphosyntax to anticipate correct picture selection in a native-like fashion, suggesting that bottom-up processing is sufficient for the detection of violations in L2 reading. The results also showed that individual cognitive factors and language experience other than proficiency had minimal effects on performance. Taken together, these findings support the notion that L2 processing strategies are not inherently different from L1 strategies but are dependent on L2 experience. [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://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]