The importance of the peer relationship has been discussed since 1970\u27s, as a part of the development of the infants\u27 social skills to interact with others, which had been almost disregarded for the past 30years. While a great amount of evidence has been provided to support the fact that young infants such as toddlers do interact with peers, some new issues have been coming up. One of them is what condition can facilitate their interaction. In particular, we have received several different points on the role of toys in the interaction of toddlers. We undertook an observational study of young infants to focus on this point. 16 home fostered subjectsin 8pairs at the ages of 18, 21 and 24 months old were observed in the 3 different toy conditions (with no toys, portable toys and non-portable toys) in the playroom free-play situation in 1985-6. Each infant has a same-sex, same-age, unfamiliar peer as its partner. The present paper is our first report of this project. We analysed a part of 18 months olds\u27 data. These were the time-sampled data of the toddlers\u27 peer-oriented behaviors and the minute note records of their interactions. The conditional effects to their behaviors and interactions, especially to their intentions to initiate interactions, were discussed
