This study aimed to analyze the adaptive skills of children with intellectual disabilities in institutional care. We focused on communication, socialization, daily living skills and their relationship with risk factors, and institutional care. Our sample included 197 children aged 5–18 years (M = 12.8, SD = 2.97), 50% boys, with IQ < 85 placed in different types and lengths of stay in institutional care. There were 17% that presented with borderline intellectual functioning (IQ 84–87) and 83% that had intellect disabilities. Adaptive behavior (AB) was assessed by Vineland Adaptive Behavior Scale (VABS-3). The BIF and Mild ID groups did not differ in Socialization. The profile of adaptive behavior for BIF and Mild ID was Daily Living Skills > Communication > Socialization, and for Moderate and Severe ID, Socialization > Daily Living Skills > Communication. Longer institutional care was associated with lower competencies in AB. Gender differences were found, females overperformed males in Socialization, Daily Living Skills, and ABC score. Levels of ID, gender, length of stay in institutional care, and neonatal difficulties were significant predictors in the model which explain the 63% variance of AB. The practical implications of the results are discussed related to the assessment of ID, prevention, and care for institutionalized children.