Papua New Guinea (PNG), an independent state in the southwest Pacific, is the most linguistically diverse country in the world. Its roughly six million people speak over 800 distinct languages. In spite of this diversity, in 1995 the Papua New Guinean government established a mother tongue-based bilingual education programme in which community languages are taught as a subject and used for instruction in the first three years of formal education. English is introduced as a subject in the third year of school and becomes one of the languages of instruction, with the community language, in early primary. In grades seven and eight, teachers use only English for instruction, although community languages can still be used informally. By the early 2000s, over 400 languages were being used in PNG's formal education system. This paper describes the background to PNG's bilingual education programme, then provides an overview of its main features and the positive outcomes as well as the problems encountered since it was initiated 15 years ago.