Early language aptitude tests were generally tests of ability in English or work-sample tests in the target language or an artificial language. Recent work has involved various correlational studies and factor analyses to determine what factors correlate most with success in foreign language learning. Approaches include: (1) correlations of several language aptitude tests with the U.S. Air Force Schools English Comprehension Level Tests to study English learning ability in foreign students; (2) a predictor study using the vocabulary and paragraph reading sections of the Pennsylvania State College Academic Aptitude Examination, and (3) a study involving work-sample tests and artificial languages. Factor analytic studies seem of greater relevance now, to analyze and measure abilities constituting language aptitude. A study by Gardner and Lambert analyzed 24 variables of language skills and mental abilities and identified four as indices of second language skills. A study by Pimsleur, Stockwell and Comrey concluded that verbal intelligence and motivation were the main success factors. The Modern Language Aptitude Test consists of five subtests concerning number learning, phonetic script, spelling clues, words in sentences and paired associates. Reviews of the MLAT indicate that it is probably the most effective available, but criticize certain aspects. (CHK)