Second language anxiety has a debilitating effect on the oral performance of speakers of English as a second language. This article describes a research project concerning the conceptualization of second language speaking anxiety, the relationship between anxiety and second language performance, and the major reported causes of second language anxiety. The participants in this study were advanced English for academic purposes (EAP) students studying on intensive EAP courses immediately prior to entering Australian universities (N = 275). The second language speaking anxiety scale (SLSAS) was developed for the study. This instrument provided evidence for a dual conceptualization of anxiety reflecting both oral communication within and outside the language learning classroom. The scale was validated using confirmatory factor analysis. The analysis indicated second language speaking anxiety to be a significant predictor of oral achievement. Reported causes of anxiety were investigated through interviews. The results indicate that the most frequent source of anxiety was interacting with native speakers. Evidence for two types of anxious language learner emerged; retrieval interference and skills deficit. There was an indication from the study that English language learners from Confucian Heritage Cultures (CHCs), China, Korea and Japan were more anxious language learners than other ethnic groups. (Contains 7 tables and 1 figure.)