[4][5] Developing language proficiency improves an individual’s capacity to communicate.
Over time through interaction and through exposure to new forms of language in use, an individual learns new words, sentence structures, and meanings, thereby increasing their command of using accurate forms of the target language.
[6][7] Note that test scores may not correlate reliably, as different understandings of proficiency lead to different types of assessment: The American Council on the Teaching of Foreign Languages (ACTFL) distinguishes between proficiency and performance.
In part, ACTFL's definition of proficiency is derived from mandates issued by the U.S. government, declaring that a limited English proficient student is one who comes from a non-English background and "who has sufficient difficulty speaking, reading, writing, or understanding the English language and whose difficulties may deny such an individual the opportunity to learn successfully in classrooms where the language of instruction is English or to participate fully in our society".
ACTFL views "performance" as being the combined effect of all three modes of communication: interpretive, interpersonal, and presentational.