This paper investigates the effects of self-efficacy and willingness to communicate on English speaking skills in a Japanese university Media English course. Social cognitive theory (Bandura, 1986), as well as studies in educational psychology (Pajeres & Schunk, 2001; Schunk & Hansen, 1985), have suggested that self-efficacy, i.e., learners' judgments about their abilities to successfully complete a specific task (Paulsen & Gentry, 1995; Schunk, 1996), has a direct impact on academic performance. However, studies of foreign language learning have been limited with respect to self-efficacy. In addition, studies in second language acquisition (Hashimoto, 2002; Matsuoka, 2006) indicate that L2 confidence or self-efficacy influences WTC, which in turn predicts English proficiency. Based on these empirical results, a model in which self-efficacy influences WTC and L2 speaking skill development was hypothesized and tested statistically. The investigation was conducted with 285 second-year English majors and the data were collected using two different questionnaires and an in-house proficiency test. Results indicated that self-efficacy predicted L2 speaking skills and influenced willingness to communicate, which in turn, predicted L2 speaking skills as well. Thus, the hypothesized model was supported.