This dissertation research aims to better specify the role of context in the development of second language interactional competence. Drawing on conversation-analytic methods and Wong and Waring's (2010) model of interactional practices, I described and compared the opportunities that two study abroad contexts--the homestay and the language classroom--afforded one language learner to participate in one set of interactional practices--the initiation of new topic talk--throughout a semester-length study abroad program. Specifically, I sought to determine: (a) which methods the participants deployed to initiate new topic talk in each context; (b) which topic initiation methods were deployed exclusively by the learner, exclusively by the proficient speaker, or by both learner and proficient speaker in each context; and (c) how the participants sequentially organized each method of topic initiation in each context. The first set of analyses revealed that the participants made use of five distinct topic initiation methods and that all five methods appeared in both the homestay and the language classroom. The second set of analyses revealed that the affordances for participating as an initiator of new topic talk differed systematically by context, whereby the learner was observed to deploy a wider range of methods for initiating topic talk in the homestay as opposed to the language classroom. The third set of analyses revealed similarities and differences in the ways in which the participants organized topic initiation sequences across the two contexts. With respect to similarities, topic initiation methods appearing during casual pre-class talk interactional periods in the language classroom were often organized using the same basic sequences of turns that were observed in the homestay. Differences, meanwhile, included: (a) variations in sequential trajectories stemming from differences in participation frameworks (i.e., dyadic in the homestay vs. multiparty in the language classroom); (b) differences in the organization of methods between the homestay and pedagogically-oriented mid-class talk interactional periods; (c) differences in the range of topicalizable items; and (d) differences in the activities to which topic talk was directed. The observed differences in both the distributions and organization of topic initiation methods across the two contexts provide evidence that different learning contexts may afford learners differential opportunities for participating in second language interaction. [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.]