English has become an international language, widely used in business, academia, and tourism. Many people learn English as a second language to improve their employment prospects and communication skills. Therefore, the education sector has focused on enhancing the value of English. New teaching strategies have been applied at different educational levels. Along with that, at the high school level, the development of soft skills such as teamwork, project management, communication, and problem-solving skills is limited. This study aims to determine whether the Project Based Learning (PBL) method should be applied to Content and Language Integrated Learning (CLIL) lessons to improve the soft skills for 10th-grade students. Data was collected through questionnaires and surveys with 30 participants from a high school in Vietnam. The results showed that students' soft skills improved after applying PBL to CLIL lessons. Student feedback was generally positive, and suggestions to reduce barriers to adopting these methods were offered to increase effectiveness and widespread adoption.
