Foreign language aptitude was the subject of much research in the 1950s and has been the subject of intermittent research for the last 30 years. Aptitude is measured by the amount of time it takes an individual to learn. Foreign language aptitude appears to differ from general aptitude or intelligence. One theory states that foreign language aptitude consists of four cognitive abilities: (1) phonetic coding, or the ability to segment and identify distinct sounds, form associations between the sounds and their symbols, and retain these associations; (2) grammatical sensitivity, or the ability to recognize the grammatical function of words or other linguistic structures in sentences; (3) rote learning ability in foreign language situations; and (4) inductive language learning ability, or the ability to infer the rules governing language use. Several tests of foreign language ability are in use today for a variety of purposes in government and education. Concerns about the age of currently used language aptitude tests and the need to incorporate new knowledge of aptitude into test design suggest a need for research, test development, and data collection and analysis. The concept of language aptitude may need to be expanded and refined. (MSE)