This study compares interactions between infants and parents to interactions between infants and strangers. Infants from 2 weeks to 6 months of age were taped in face-to-face interactions with unfamiliar male and female adults. Tapes of parent-infant interactions were available from a prior study. Specific infant and adult behaviors were coded and recorded from these tapes. The adult behavior variables recorded included gaze direction, body position, touch pattern, facial expression, movement and vocalization. Infant variables were gaze direction, facial expression, movement and vocalization. The organization of these behaviors was further defined by a phase anlaysis. The phases studied included avoid/protest, avert, monitor, elicit, set, play and talk. Analysis of the specific behaviors and phases indicated significant differences between infant-parent and infant-stranger interactions. Interactions between infants and strangers revealed a lack of synchrony and a lack of accommodation of behaviors between the partners. Phase analysis indicated predominantly neutral and negative phases during the infant-stranger interactions. Results suggested that infant social interactions at these age levels are neither random nor indiscriminate but are highly specific to the behavior setting. (BD)