An ongoing series of studies at the University of Illinois at Urbana-Champaign concerning cross-cultural interpretation of implicature in conversation is discussed. Implicature is defined as the process of making inferences about the meaning of an utterance in the context in which it occurs. The studies focus on non-native speakers' (NNSs') interpretation of implicatures in American English. The first two studies, in 1986-91 (n=436 NNSs) and 1990-93 (n=304 NNSs), found that NNSs can develop a high level of proficiency in interpreting implicatures if given enough time, and that the amount of time required depends on implicature type, formulaic or relatively non-formulaic. The third study (1993) with 14 international students in an academic English course investigated whether classroom instruction on specific rules and patterns of implicature could speed acquisition of interpreting skills. Results suggest that formal instruction can be effective when focused on the more formulaic implicatures, while the less formulaic forms were as resistant to formal instruction as they appeared to be, in earlier research, to natural learning processes occurring in the American academic environment. Contains 11 references. (MSE)