This study explored the English writing strategies of Korean university students by focusing on the relationship between their study abroad experiences and English writing strategies. The theoretical framework for this study is activity theory. Activity theory explicates social phenomena including human learning, by the interaction of social members through media such as tools and symbols, emphasizing the social context in human activities. Ten Korean university students learning English as a foreign language (L2) participated in this study. Five students had study-abroad experience (Group A), while the other five students (Group B) had not studied abroad. They wrote five English essays and one personal narrative regarding their English writing experience. Their writing strategies were collected by a variety of channels such as questionnaire, interviews, process logs and stimulated recalls. The results indicated that studying abroad affected Korean university students' English writing strategies (e.g., rule mediated strategies, community-mediated strategies, role mediated strategies, and goal mediated strategies). This study drew some ideas from community-mediated strategies and goal mediated strategies, which could be pedagogically applied to English education.