Subjected 102 boys and 87 girls (aged 11-19 mo) to the Strange Situation (M. D. Ainsworth and B. A. Wittig, 1969) to study Ss’ interaction patterns with a parent and a stranger and reactions to differences in strangers’ styles. Boys and girls reacted differently to different strangers. Boys showed more resistance and avoidance to strangers who used more direction and initiation; girls did not react this way. 18-mo-old Ss showed more variations in their reactions to different interactional styles than did 12-mo-olds. Results are discussed in terms of the child’s expectations of sex-determined styles of interaction learned from past social interactions.