The present study explores the influence of sibling's presence on children's social adjustment, measured by the behavioral flexibility of 83 five-year old children from Cadiz (Spain). The variables tested were a) mother's educational level, b) mother's work outside of the home, and c) children's kindergarten attendance. The results showed the necessity of considering further variables of family background in order to create a model that explains the effect of the number of siblings on children's social adjustment. Thus, the presence of the mothers at home (who do not work outside of the home) positively influences the social adjustment only of the first born and/or only children. However, in the later born children this fact has a smaller effect because of the presence of older siblings. Independent of mother's educational level, kindergarten attendance favors the social adjustment of only children. Key words: number of siblings, social adaptation, behavioral flexibility, andalousian preschoolers, Spain.

Peer Reviewed