To look at continuity and change in play, children were observed in a natural setting using an observation schedule which allowed for coding their behavior and reactions to that behavior by others in the environment. The behavior scores were factor analyzed with six factors (play styles) resulting. This paper discusses a group of 67 boys and girls who entered the play groups between 18 and 24 months of age and who remained with the groups for a period of at least one year. Children who were high and low on each factor upon entry to the groups are examined in detail. Changes in play styles over the period of a year were predictable from peer and teacher reactions. In particular, the male peer group was extremely effective in shaping male sex-typical behavior, even when the boys entered the play group with other styles of play.