This study examined children's expectancies about interactions with own- and other-gender peers. Goals were to examine expectancies about the outcomes related to own- versus other-gender group interactions, assess cohort and temporal changes in expectancies, and assess the effect of expectancies on school-related outcomes. Students in second and fourth grades (N = 412, 47% girls, M[subscript age] = 7.15 and 9.10 years, respectively) were followed longitudinally for 1 year. Results supported hypotheses that social costs and inclusion-enjoyment that children expect in interactions with own- and other-gender peers represent four constructs. Expectancies varied by gender, age, and differentially predicted school outcomes with inclusion expectancies more strongly relating to outcomes than cost expectancies. Implications of children's expectancies about gendered contexts are discussed.