Objective: Survivors of pediatric brain tumors are at increased risk of executive function (EF) and adaptive behavior difficulties. While previous research suggests that executive dysfunction impacts suboptimal adaptive outcomes, the specific elements of EF influencing this relationship remain unexplored. This study examines the relationship between cognitive flexibility and adaptive behavior in survivors compared to healthy controls. Methods: 86 survivors (M age(SD)=23.41(4.24), 44 females) and 86 controls (M age(SD)=23.09(4.50), 44 females) completed the Delis-Kaplan Executive Function System Trail Making Test (TMT) and Verbal Fluency Test (VFT). The Letter-Number Sequencing (LNS) and Category Switching (CS) conditions were isolated as measures of cognitive flexibility. Informants provided responses to obtain adaptive behavior ratings using the Scales of Independent Behavior-Revised (SIB-R). Linear regressions explored relationships between cognitive flexibility and SIB-R scores in survivors compared to controls. Results: For both TMT and VFT, the relationship between cognitive flexibility and adaptive behavior was significantly different between survivors and controls for SIB-R scores in Social Communication, Community Living, and Personal Living Skills (p<.0125). Survivors’ better LNS performance predicted greater SIB-R scores across the same 3 domains (all p= <.001, r 2semipartial=.08). Similarly, survivors’ better CS performance predicted greater SIB-R scores across the same 3 domains (p = 0.002 to .02, r 2semipartial =.03 to .04). No significant relationships were found in controls (all p >.05). After adjusting for working memory and inhibitory control, most relationships remained significant in survivors (p= <.001 to .046, r 2semipartial=.02 to .08). Conclusion: These findings reveal a robust, positive relationship between cognitive flexibility performance and adaptive behaviors specific to survivors.