This mixed-methods study examined the beliefs and performance of 10 adult Japanese speakers of English regarding the phenomenon of contraction in spoken English. Over the course of three months, a collective case study approach involving listening tasks and semi-structured interviews was employed to investigate the topic from multiple dimensions, both qualitatively and quantitatively. In addition to the creation of individual portraits of these English learners by exploring their unique learning histories, and their oral/aural performance, similar performance data collected from four native English speakers were used to further contextualize the Japanese participants' results. Analysis revealed distinct tendencies regarding contraction production and perception ability as they relate, for instance, to contraction type and the ratio of contraction. The research also uncovered common themes regarding general and individual-specific contraction-related beliefs. These findings can serve as a touchstone for researchers and educators concerned with the English oral/aural development of Japanese learners, specifically with regard to contraction-related issues affecting them. [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.]