Late second language (L2) learners often struggle with L2 prosody, both in perception and production. This may result from first language (L1) interference or some property of how a second language functions in a late learner independent of what their L1 might be. Here we investigate prosody's role in determining information structure through focal stress. In particular, this thesis compares L1-Mandarin/L2-English and native/L1-English speakers' perception and production of English focal stress, namely how both groups process focal stress, how that processing affects eye movements, and how the various aspects of focal stress production between groups. Our first two experiments targeted the perception of prosody, and the third targeted production. The two perception studies used high temporal resolution experimental methodologies--event related potentials (Exp. 1) and eye-tracking (Exp. 2). The ERP experiment probed question-induced focus and prosodic marking of accent, monitoring brain responses during detection of question/answer incongruities. The eye-tracking experiment targeted accent marking in the scope of the focus-sensitive element only. Eye movements were monitored while participants performed an auditory/visual truth value judgment task. In a related production experiment (Exp. 3), participants were given a written sentence whose meaning hinged on focal stress. Their attention was then directed to a picture which depicted one of two possible interpretations, and they were tasked with producing the sentence so it would describe/match the picture. Though L2 learners exhibited poorer performance comprehending and producing focal stress, they could nonetheless perform at advanced levels. However, online (ERP/eye-tracking) measures show a delay in processing of focal stress and a lack of interaction effects between Focus and Accent that obtains in native speakers. In production, L2 learners produced weaker, but in several ways "native-like", focal stress, including an L1 pattern of not distinguishing nominals in the second position of ditransitives ("Steve only gave Boris the bulldog."/"Steve only gave the bulldog to Boris.") via prosody independent of expected focus (i.e., an interaction between focus-marking and word order). The combined findings show that though late L2 learners can perceive and utilize prosodic accent, they have difficulty integrating that information in incremental/real-time processing. Further, effects of Age of Acquisition, but not proficiency, on some of our observed response profiles are discussed in the context of Critical/Sensitive Periods in second language acquisition. [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.]