The report describes a federally funded study of the application of language proficiency concepts, developed for commonly taught languages, to less commonly taught languages. It summarizes the project's background and origins and the activities of the project, including four separate studies on the feasibility of proficiency-based instruction and testing in Arabic, Hindi, Indonesian, and African languages as a group. In each study, a workshop or demonstration of proficiency testing was held for language teachers and linguists and recommendations for further study and action were made. The report also describes the final project activity: publication and dissemination of a volume of working papers that includes the four language-specific study reports, the 1986 American Council on the Teaching of Foreign Languages' Proficiency Guidelines, and five papers on aspects of proficiency-based instruction and assessment. A mailing list for the project volume is appended. (MSE)