Research Findings: Sibling pretend play, collaboration, and creativity during maternal presence and absence were investigated in 24 dyads in early and middle childhood (younger siblings' M age = 5.3 years; older siblings' M age = 8.2 years). Associations between sibling behavior and maternal interaction (e.g., guidance, positive responses) were also examined. Creativity was assessed by (a) the number of object transformations, (b) pretense themes (set-up, typical, creative), and (c) use of descriptive language (i.e., adjectives). Findings indicated that maternal presence had an inhibitory impact on the frequency of sibling pretense, collaboration, and measures of creativity. Creativity measures were positively associated both within and across play sessions. Although maternal guidance was generally not associated with sibling interaction, maternal positive responses were associated with the younger sibling's behavior, suggesting that most mothers were responsive but not actively engaged in their children's play. Practice or Policy: Findings are discussed in light of recent research and theory; implications for practice are considered. (Contains 3 tables.)