In communication between first (L1) and second (L2) language users, the default has long been for L2 speakers to assume most, if not all, responsibility for adjusting their speech to accommodate their interlocutor. This not only places an undue burden on the speaker, but also furthers the assumption of listener passivity in communication. One approach to addressing these issues is through listener training that helps L1 listeners develop the appropriate communicative tools to be active partners in crosslinguistic communication. Implicit training approaches have demonstrated success in improving attitudes toward L2 accented speech (Kang et al., 2015; Lindemann et al., 2016). However, little is known about how these trainings impact listeners' cognitive processing of L2 accented speech or how listener individual differences affect these training outcomes. The current dissertation study examined the effectiveness of an exposure-based online listener training program by measuring listeners' processing and perception of L2 accented speech, along with key individual differences (i.e., accent familiarity, Big Five personality traits, linguistic stereotyping, and willingness to communicate/listen). Seventy-one L1 English listeners were recruited and randomly assigned to a two-week program exposing them to either a) L2-accented English varieties or b) traditional L1 English listening comprehension tasks. Before and after the training program, listeners completed a true/false task measuring their response time, processing stability, and response accuracy, as well as a speech rating task with measures of comprehensibility and strength of accent. Data were modeled in a series of linear mixed-effects models.Results indicated that cognitive processing measures were predictive of strength of accent ratings but not comprehensibility. Individual differences in accent familiarity and linguistic stereotyping emerged as salient predictors of cognitive processing and perception. Finally, both experimental (accent familiarity) and comparison (L1 English-only) participants displayed improvements in cognitive processing as a result of training, while experimental participants had an added benefit in perceived strength of accent ratings. Findings of this study inform future approaches to listener training, accent familiarity measures, integration of psycholinguistic methods, and pedagogy. [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.]