The purpose of the present study was to explore the antecedents influencing the implementation and the outcomes of the middle school English language curriculum. Case study was adopted to deeply explore a phenomenon, which can be the processes, events, persons, curricula, or things of interest to the researcher. The phenomenon, in this study, is the middle school English language curriculum. Four English teachers teaching different grade levels from a middle school located in Ankara were participants of the study. The data collection instrument was a semi-structured interview developed by the researchers. The interview schedule included 11 main questions and some probing questions to explore the antecedents that might have influence on the implementation of the curriculum. Data collected through interviews were analyzed with content analysis. Content analysis revealed four categories (themes) which were named as "teacher characteristics", "student characteristics", "school characteristics", and "teachers' views about the curriculum". Findings indicated that rather than one factor, the combination of the four factors influence teacher and student behaviors which in turn influence the implementation process and the overall success of the curriculum.