The present study examines the link between children's number of older siblings and their cognitive development, as measured by executive function (EFs) skills and verbal skills (VIQ) in a sample of 1,302 4-year-old children (54% boys) living in rural Pakistan. Specifically, we investigate whether the links between the number of older siblings and preschoolers' EFs and VIQ are moderated by preschoolers' quality of home stimulation and gender. Multivariate regressions revealed that the number of older siblings was positively associated with EFs for boys in homes with both higher and lower levels of stimulation, and for girls in homes with lower levels of stimulation (p < .05). However, the number of older siblings was negatively associated with EFs for girls from homes with higher levels of stimulation (p = .03). Further, the number of older siblings was positively associated with VIQ in homes with lower stimulation (p < .05), but not for higher stimulation homes. Gender was not a statistically significant moderator of the association between the number of older siblings and VIQ. Findings suggest that living with more older siblings may promote emerging EFs and VIQ among boys and girls with fewer opportunities for cognitive stimulation. However, more older siblings may hinder EF development for girls in the context of adequate home stimulation, perhaps due to inequitable allocation of resources among boys and girls in more affluent, larger families. (PsycInfo Database Record (c) 2023 APA, all rights reserved).