Two studies of individuals' oral second language performance in interaction with extraverts and introverts are reported here. The first, described briefly, investigated the effects of homogeneous (extravert/extravert or introvert/introvert) vs. heterogeneous pairings on oral performance in interviews. Subjects were 36 women students in a Japanese college. As predicted, introverts performed best in homogeneous pairs and somewhat less well in heterogeneous pairs, while extraverts performed best in homogeneous pairs; neither group performed as well in individual interviews. The second study investigated the hypothesis that individual learners of a second language would perform differently on a group oral test depending on the degree of extraversion of the individual in relation to economics students in an English enhancement course. Students had been assigned randomly to seminar groups, which were then rated for extraversion/introversion. Results indicate that the degree of extraversion in the group produced no significant differences in the scores of extraverts, while those of introverts were considerably affected. These apparently contradictory findings are discussed, particularly as they relate to a trend toward paired and group teaching. Contains 48 references. (MSE)