This study investigates the role of context of learning in second language (L2) acquisition. Participants were 40 native speakers of English studying Spanish for one semester in one of two different learning contexts--a formal classroom at a home university (AH) and a study abroad (SA) setting. The research looks at various indexes of oral performance gains--particularly gains in oral fluency as measured by temporal and hesitation phenomena and gains in oral proficiency based on the Oral Proficiency Interview (OPI). The study also examines the relation these oral gains bore to L2-specific cognitive measures of speed of lexical access (word recognition), efficiency (automaticity) of lexical access, and speed and efficiency of attention control hypothesized to underlie oral performance. The learners also provided estimates of the number of hours they spent in extracurricular language-contact activities. The results show that in some respects learners in the SA context made greater gains, both in terms of temporal and hesitation phenomena and in oral proficiency as measured by the OPI, than learners in the AH context. There were also, however, significant interaction effects and correlational patterns indicating complex relationships between oral proficiency, cognitive abilities, and language contact. The results demonstrate the importance of the dynamic interactions that exist among oral, cognitive, and contextual variables. Such interactions may help explain the enormous individual variation one sees in learning outcomes, and they underscore the importance of studying such variables together rather than in isolation. (Contains 1 footnote.)