Discussion of the use of language aptitude tests for United States government workers looks at the learner types they must assess and contexts in which a newly-learned language will be used. In general, employees selected for language learning are either current employees already productively engaged in second language use or new hires with excellent academic records in commonly taught languages. Training focus is primarily on speaking, non-interactive listening, and reading, targeting a minimum proficiency level of 2. For less commonly taught languages, however, there are few measures to predict success beyond this level. Skills required for speech and writing are linked to different social dynamics characterizing each. The complex relationship of these two channels of delivering language has important implications for aptitude testing. Distance between the learner's existing second language is also a critical factor in language aptitude and training; a new technique for measuring third language difficulty is now available. There are complex relationships between the backgrounds and attainments of prospective language learners and frames of reference in which they will be expected to operate. A variety of instruments is needed, some of which will demand much more testing time and may discomfit personnel preferring quick testing. (MSE)