Global realities of the 21st century present new challenges for every discipline, and world language is no different. In a time when students need to graduate prepared to relate to, study with, and work with people of different linguistic and cultural backgrounds in order to solve global problems and explore new possibilities, world language educators must stop and ask themselves how they can be more effective in helping students develop a 21st century skill set in languages and cultures. Simultaneous to these new realities is the growing body of research that points to teacher effectiveness as the single most critical factor in student achievement. Research shows that it is not the particular school that students attend, or the size of the school or even the size of their classes that impacts learning nearly as much as the effectiveness of the teacher. And while a solid foundation in subject matter content is clearly important for any teacher, research suggests that it is not so much what the teacher knows but what the teacher does in the classroom that maximizes student achievement. High levels of student achievement are critical to individuals, to society and to a nation’s standing among the other nations of the world, and it is the effectiveness of teachers that ensures high student achievement. What, then, makes an effective world language teacher? Although a great deal is known about effective world language teaching, the collaborators of the TELL Project discovered that there is no one place where the characteristics and behaviors exhibited by effective world language teachers are clearly defined. If the profession needs world language teachers to do their part in effectively preparing students to live in a world of increasing international interactions, then it must be able to clearly state what it means to be effective. In other words, what do effective world language teachers do to ensure that students achieve world language competence?