Despite a strong pedagogical orientation, the majority of research examining the effectiveness of task‐based language teaching (TBLT) and perceptions toward TBLT has been investigated in isolation rather than embedded in larger curricular contexts (McDonough, ). The current study examines the process of developing a TBLT curriculum in South Korea and evolving perceptions toward this particular semester‐long task‐based course of students from one intact university class. Dynamic systems theory is used to investigate students’ evolving perceptions of the new task‐based course using two longitudinal data sources, surveys and portfolios. End‐of‐task unit surveys from 27 students and one focal participant's portfolio entries were analyzed both quantitatively and qualitatively. Findings demonstrate that students’ perceptions toward TBLT changed over time and that diverse factors affected how learners feel about task‐based instruction. Findings are discussed in light of developing localized TBLT curricula.