Evidence for the existence of sex differences in children's ethnic & lang attitude development is reviewed, focusing on the results of a study conducted with bilingual Franco-Ontarian children in Welland, Canada (N = 147 Ms, 146 Fs, ages 3-12, all attending French-lang nursery or elementary schools). In a 10-item questionnaire, Rs expressed preferences for Eng- or French-speaking stimuli in a puppet-show presentation. Findings indicate: (1) in the youngest group, boys expressed significantly fewer ethnocentric preferences than girls; & (2) older children showed equally high in-group preferences, with girls' responses approximately stable across age groups. Further discussion includes a review of sex-differentiation attitude research among adults; additional study is recommended on the interaction of ethnic/linguistic with SE & group solidarity factors in attitude development. 1 Table, 1 Figure. L. Whittemore.