ABSTRACT The ACTFL Provisional Proficiency Guidelines, a series of proficiency levels for speaking, listening, reading, writing, and culture in a foreign language, are a guiding principle for the development of communicative, proficiency-oriented tests and curricula. Based on proficiency descriptions originally developed by the U.S. government, the guidelines at each level include statements of characteristic linguistic functions, content areas, and accuracy. The features of proficiency and achievement tests are discussed, and two proficiency-based curriculum projects are described.