The researcher proposes, in this paper, her action research with a quasi quantitative and qualitative design, to provide some important insights into the use of journal writing as a means to improve grammatical accuracy of first-year university Thai undergraduates with no prior exposure to journal writing in English. The data on the undergraduates’ grammatical accuracy were analyzed through their journal entries covering both dialogue-journaling and process-writing entries, while their opinions of journal entries and grammatical accuracy were obtained through their dialogue journaling entries and interview responses. Findings are discussed, and recommendations for future research are made. It is also hoped that journal writing can be another useful learning activity and a teaching alternative to enhance EFL undergraduates’ grammatical accuracy in English.