This study aims to investigate EFL learners' perceptions of online writing instruction compared to traditional, face-to-face one and their writing self-efficacy under the circumstances of in-class and online writing instruction. Data were collected from 52 EFL learners having experienced both conditions interchangeably within the scope of 28-week study design. In a mixed-method research design, the participants responded to a writing efficacy scale and were interviewed following each intervention. The data analyses revealed that there was no significant difference between the writing efficacy levels of the participants in in-class and online writing instruction, but they had a lower level of efficacy for accuracy and design in writing tasks, which was expressed as the result of previous learning experience and lack of writing practice. Furthermore, the interviews revealed that they preferred in-class to online writing courses considering interpersonal skills and their need for written corrective feedback in person, implying significance of individual differences and independent learning. Based on these findings, the study proposes several educational implications.