Empirical study: Objectives and planning: The study aims to identify the personal factors that affect transitions in children's play, in order to assess which of these factors influence more intensively type of play evaluated. .Children spend several years in spontaneous play, from solitary to social play, from no pretend activity to pretend play, and within an episode of pretend play, from setup to enactment to negotiation phases (Doyle et al, 1992; Rubin y Coplan, 1998). In the present study it was hypothesized that, social play enactment would be more complex than literal social activities (e.g. language and I.Q.). The empirical study, subjects were 23 preschoolers observed playing in group, during 30 min sessions. They were assessed with WIPPSI, and continuous recording was made of the activity of play in the group (e.g. social - solitary, negotiation of pretend and the social interaction). Results of solitary-social play: After video and in vivo training on coding behaviors according to operational definitions, inter.-observer reliability was calculated; percentage agreement average Kappa (Cohen, 1960) was .83. In order to isolate the important dimensions of the numerous observational predictor variables and the personal factors, each set of variables was analyzed. The pattern of transitions between prior and subsequent activity modes was of principal interest (Gottman & Roy, 1990). The transitions that occurred significantly more frequently than expected are social play. That is, negotiation and social interactions of social play (F(2, 15) = 5.493, p = .01, R2 = .423, Durbin-Watson = 2.225). The personal factors I.Q. (5 subscales Information, vocabulary), and social play of frequent pretenders was more often that of solitary play (F(4, 17) = 2.979, p = .049, R2 = .412, Durbin-Watson =1.829). Conclusion: The varied social interactions we have described in this study illustrate the social interactions and I.Q. as a fundamental ingredient of pre schoolers' play. Thus, negotiations and interaction social of social play was important precursor of pretend enactment.