This open-source Intermediate Vietnamese textbook is task-based, with a focus on authentic materials and tasks necessary for the students in real life. The textbook is designed following the Task-Based Language Teaching principles with a focus on using authentic materials to maximize opportunities for learner proficiency development. Tasks of various modes of communication are organized and sequenced through topics and themes. As for the structure of the material, the textbook is a loosely sequenced set of task-based materials which allow instructors to adapt easily to their specific teaching contexts.