An examination was made of peer social interaction in the first year of life (8 - 10 months) with regard to: 1. the content of iteractions; 2. the effects of partner familiarity on interactions. Five infants were also observed in a pair, at 8 and 10 months of age, respectively before and after a period of familiarization. The same infants were observed in a pair with an unfamiliar peer in the same conditions. All the infants showed an increasein positive social interactions and a decrease inm negative interactions with the familiar partner; then opposite occurred with the unfamiliar one.
