This study compares the face-to-face interaction of infants with fathers to their interaction with mothers and with strangers. Five infants were videotaped in individual interaction with their mothers, fathers, and unfamiliar adults at weekly intervals from the second week until the infants were 6 months old. Infants were seated in a laboratory setting with the parent or stranger opposite. Sixteen sessions, each consisting of a 2-minute period of "playful" communication with the adult, were examined for differences in interaction. The film demonstrated that infants display a different behavioral repertoire and have a different expectancy for interaction with fathers as compared with mothers and strangers. A further second-by-second slow motion videotape analysis was conducted utilizing the following infant and adult categories: gaze patterns, limb movements, body positions, facial expressions, vocalizations, and touching patterns. Results indicated that differences in infant response to fathers, mothers and strangers are apparent as early as 4 weeks. In addition, the responses suggest that infants expect and elicit different kinds of interaction with different adults: with mothers, a reciprocal, contained type of interaction, while with fathers, a more heightened, alert, playful interaction. In contrast, the stranger serves as a source for cautiously testing newly acquired social skills. The unique roles mothers and fathers can play with young infants are stressed. (CM)