14 peer dyads were observed longitudinally at 16, 20, 24, 28, and 32 months to assess developmental changes in social coordinations (both action-to-action thematic relations and extended games). Each child's movements through the playroom, actions upon play material, vocalizations, verbalizations, and gestures were coded for their relation to the concurrent or immediately prior behavior of the peer: Unrelated, Tangential, Coordinated, Interfering. There was a marked increase with age in acts coordinated with those of a peer, and imitations of the peer's nonverbal actions accounted for most of the developmental change. The use of words to direct the peer in a coordinated way increased with age but remained infrequent. Developmental change in the frequency of games paralleled that for imitative acts, and imitative acts both established and set the theme for most of the games. Thus, imitating another's nonverbal actions is a core behavioral strategy for achieving social coordinations during the developmental period preceding reliance on verbal communication in peer interaction.