This paper examines the longitudinal changes of Korean college students in their motivation and their self-confidence in an online-offline blended EFL-learning course. The participants completed the same questionnaire three times (i.e., March, June, and December) with items regarding the ideal second language (L2) self, the ought-to L2 self, instrumentality, integrativeness, demotivation, and the perceived confidence in speaking English. Repeated-measures t-test/ANOVA indicated that students' initial motivation was maintained until the end of the academic year. Their confidence in speaking English increased in a statistically significant manner. However, student demotivation also increased despite the fact that it remained at a relatively low level. These findings portrayed that the online-offline blended English learning was an effective instructional medium for EFL students in their English courses. This study suggests that L2 practitioners need to find an optimal balance between online instruction and offline EFL classes, where in-class authentic L2 communication should be maximally fostered.