The authors examined factors related to preschool children's reasoning about including a hypothetical peer with a physical disability in different play activities. They hypothesized that children's inclusion decisions would be influenced by features of the physical environment, attention to issues of fairness and equity, and individual child characteristics. Participants comprised 72 children enrolled in inclusive preschool classrooms. Children's ideas about inclusion and their inclusion decisions were gathered in response to vignettes reflecting experiences that children are likely to encounter in preschool. The authors found that children were significantly more likely to say that they would include a child with a physical disability in an activity requiring few motor skills. Children's inclusion decisions were also significantly associated with their developing theory-of-mind skills and with prompts that encouraged them to consider issues of fairness and equity when making a decision. These results suggest that adaptations of planned activities that promote participation by reducing motor demands for all children, along with attention to issues of fairness and equity of opportunity, may be effective classroomwide interventions to support inclusion of children with disabilities in play activities with peers. (Contains 2 tables.)