Background: Adaptive behavior, i.e., the performance on daily activities required for personal and social independence, is essential to estimate in children with low-grade glioma (LGG) since most of them are long-term survivors. Our aim was to investigate adaptive behavior in children with LGG. Methods: In a cross-sectional study, adaptive behavior was assessed using the paper pencil version of the Parent Form of the Vineland Adaptive Behavior Scales 2nd edition (VABS-II) testing communication, daily living skills, social skills, and motor skills. Scores of children with LGG, younger than 20 years, and diagnosed between 2004 and 2014 were compared with family controls. Correlations between clinical variables and adaptive behavior were explored. Results: Fifty-six children with LGG (median age, 12.1 years; 52% male) and 46 controls (median age, 11.0 years; 43% male) were included in the analyses. Compared with controls, the LGG group was more impaired on total adaptive behavior, communication, and motor skills and in the subdomain gross motor skills (effect sizes d, 0.64–0.86, P < 0.003). Younger age at diagnosis (r = −0.357, P < 0.01) and chemotherapy (r = −0.342, P < 0.05) were associated with poorer motor skills. Residual disease was associated with poorer total adaptive behavior (r = −0.282, P < 0.05). No other significant correlations were found. Conclusion: At the group level, adaptive functioning of children with LGG is impaired compared with family controls. Regular structured monitoring of adaptive behavior is recommended to be able to define the needs for tailored rehabilitation in daily life at home as well as at school.