--- - |2+ Abstract Siblings offer a unique context for practising skills such as executive function (EF). Further, siblings are influential agents in parenting practices, which may, in turn, be related to EF. The current study investigated the extent to which the presence of a sibling is related to parent‐reported EF in preschoolers and whether the presence of a sibling is indirectly related to EF through global parenting practices. Participants included children 30 to 60 months old and their caregivers (n = 505). Caregivers indicated that target children were predominately White (n = 354, 72%) and African American (n = 51, 10%), with the remaining participants representing multiple other racial categories (23%). Caregivers reported on parenting characteristics, their child's EF, and demographic information. Analyses revealed a negative association between sibling presence and parent‐reported EF. Initial analyses suggested that sibling presence was indirectly related to EF through a broad measure of global parenting practices; however, Follow‐up analyses indicated that when the global parenting practices scale was broken down into distinct parenting practices (e.g., warmth), indirect effects were not significant. These findings begin to clarify the influence of parenting behaviours and sibling presence in the home on young children's EF, suggesting that continued research is necessary to further elucidate these relations. Highlights Researchers investigated the relation between sibling presence and executive function and if global parenting practices were important in the association. Caregivers reported on their child, revealing that having a sibling was associated with lower executive function. Executive function is an important predictor of numerous developmental outcomes; research must replicate our findings and continue to explore the mechanisms through which siblings may be impacting children's executive function development. - Infant and Child Development, Volume 27, Issue 4, July/August 2018.